U.S. patent number RE40,858 [Application Number 11/438,745] was granted by the patent office on 2009-07-21 for fastener element molding.
This patent grant is currently assigned to Velcro Industries B.V.. Invention is credited to Richard M. Formato, Christopher M. Gallant, Andrew C. Harvey, Stephen C. Jens.
United States Patent |
RE40,858 |
Gallant , et al. |
July 21, 2009 |
Fastener element molding
Abstract
A method of forming a mold having cavities for molding
loop-engageable, hook-shaped fastener elements, includes:
supporting a first plate having an outer surface that defines a
plane; manipulating a material-cutting beam of a laser along a
predetermined curved profile to cut a cavity into the outer surface
of the first plate, the predetermined curved profile being
generally hook-shaped, the cavity defined by a wall extending into
the first plate from the outer surface; in a series of subsequent
actions, repeatedly indexing the first plate relative to the laser
to direct the material-cutting beam at further positions on the
first plate and repeating the step of manipulating the
material-cutting beam of the laser relative to the first plate to
form a series of cavities, each having a hook-shaped profile; and
positioning a second plate adjacent the outer surface of the first
plate, the second plate providing a side wall surface for each of
the cavities of the first plate, the first plate and the second
plate in combination forming a mold having cavities for molding
loop-engageable, hook-shaped fastener elements. Various methods for
aligning such mold plates in a fastener element molding apparatus
are also provided. A hook product includes a stem portion
integrally molded with and extending from a sheet-form base to a
distal end, the stem portion having a planar side; and a crook
portion extending from the distal end of the stem portion to
overhang the sheet-form base in an overhang direction, the crook
portion having a flat planar side co-planar with the planar side of
the stem, and an upper surface extending upward from an upper
extent of the planar side of the crook portion to an apex.
Inventors: |
Gallant; Christopher M.
(Nottingham, NH), Jens; Stephen C. (Waltham, MA), Harvey;
Andrew C. (Waltham, MA), Formato; Richard M. (Grafton,
MA) |
Assignee: |
Velcro Industries B.V.
(Curacao, AN)
|
Family
ID: |
29582111 |
Appl.
No.: |
11/438,745 |
Filed: |
May 22, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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09341908 |
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6533981 |
|
|
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PCT/US98/01053 |
Jan 20, 1998 |
|
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|
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08926517 |
Sep 10, 1997 |
6039556 |
|
|
|
08786226 |
Jan 21, 1997 |
5971738 |
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Reissue of: |
10154539 |
May 24, 2002 |
06930277 |
Aug 16, 2005 |
|
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Current U.S.
Class: |
219/121.72;
493/212 |
Current CPC
Class: |
A44B
18/0049 (20130101); B23K 26/389 (20151001); B23K
26/38 (20130101); B29C 33/0027 (20130101); B29C
33/044 (20130101); B29C 33/301 (20130101); B29C
43/222 (20130101); B29C 59/025 (20130101); F28F
5/02 (20130101); B29C 43/46 (20130101); A44B
18/0061 (20130101); B29C 59/04 (20130101); B29C
2035/1616 (20130101); B29C 2043/465 (20130101); B29L
2031/729 (20130101); B29C 2043/461 (20130101); Y10T
428/24017 (20150115); B23K 2101/20 (20180801) |
Current International
Class: |
B23K
26/00 (20060101) |
Field of
Search: |
;219/219,121.67,121.72,121.85,121.6 ;493/212-214 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0709038 |
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May 1996 |
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EP |
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1042971 |
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Oct 2000 |
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EP |
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1616656 |
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Feb 2006 |
|
EP |
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2801177 |
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May 2001 |
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FR |
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10201382 |
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Aug 1998 |
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JP |
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10202382 |
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Aug 1998 |
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JP |
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WO 94/29070 |
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Dec 1994 |
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WO |
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WO 95/01863 |
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Jan 1995 |
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WO |
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WO 98/33131 |
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Jul 1998 |
|
WO |
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WO 0015069 |
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Mar 2000 |
|
WO |
|
Other References
International Search Report. cited by other.
|
Primary Examiner: Sandy; Robert J
Attorney, Agent or Firm: Fish & Richardson P.C.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
.[.This application is a continuation-in-part of U.S. Ser. No.
09/341,908, filed May 8, 2002, now U.S. Pat. No. 6,533,981 which
claims priority through PCT Application No. US98/01053, filed Jan.
20, 1998, from U.S. Continuation-in-Part application Ser. No.
08/926,517, filed Sep. 10, 1997, which issued as U.S. Pat. No.
6,039,556 on Mar. 21, 2000..]. .Iadd.Continuation-in-part of U.S.
Ser. No. 09/341,908, filed as application No. PCT/US98/01053 on
Jan. 20, 1998, now U.S. Pat. No. 6,533,981, which is a
continuation-in-part of application Ser. No. 08/926,517, filed on
Sep. 10, 1997, now U.S. Pat. No. 6,039,556, which is a
continuation-in-part of application Ser. No. 08/786,226, filed on
Jan. 21, 1997, now U.S. Pat. No. 5,971,738..Iaddend.
Claims
What is claimed is:
1. A method of forming a mold having cavities for molding
loop-engageable, hook-shaped fastener elements, the method
comprising: (a) supporting a first plate having an outer surface
that defines a plane, (b) manipulating a relative position of a
material-cutting beam of a laser with respect to said first plate
along a predetermined curved profile to cut a cavity into said
outer surface of said first plate, said predetermined curved
profile being generally hook-shaped, the cavity defined by a wall
extending into said first plate from said outer surface; (c) in a
series of subsequent actions, repeatedly indexing the first plate
relative to the laser to direct the material-cutting beam at
further positions on the first plate and repeating the step of
manipulating the material-cutting beam of the laser relative to the
first plate to form a series of cavities, each having a hook-shaped
profile; and (d) positioning a second plate adjacent said outer
surface of said first plate, said second plate providing a side
wall surface for each of said cavities of said first plate, said
first plate and said second plate in combination forming a mold
having cavities for molding loop-engageable, hook-shaped fastener
elements.
2. The method of claim 1, wherein .Iadd.said step of
.Iaddend.manipulating a relative position of a material-cutting
beam .Iadd.of a laser with respect to said first plate to cut a
cavity .Iaddend.comprises .[.moving the material cutting beam.].
.Iadd.positioning the material-cutting beam at an acute angle
relative to the plane defined by the upper surface of the first
plate to form at least a portion of the wall defining the cavity at
a corresponding acute angle relative to said plane.Iaddend..
3. The method of claim 1 wherein said step of manipulating a
relative position of a material-cutting beam of a laser with
respect to said first plate to cut a cavity comprises cutting only
partially through the first plate, a remaining portion of the first
plate providing a second side surface of the cavity, opposite said
side surface formed by said second plate.
4. The method of claim 3 further comprising a step of forming a
series of cavities on said second plate, the cavities of the second
plate being of mirror image relative to the cavities of the first
plate, said step of positioning the second plate adjacent said
outer surface of said first plate comprising aligning the cavities
of said first plate with the cavities of said second plate to form
a series of hook-shaped cavities, each having one side surface
formed by a remaining portion of said second plate and an opposite
side surface formed by a remaining portion of said first plate.
5. The method of claim 3 wherein said second plate has opposite
planar surfaces, the method further comprising a step of forming a
series of cavities extending into said second plate from one of
said opposite planar surfaces, the step of positioning the second
plate adjacent said outer surface of said first plate comprising
aligning a non-cavitated portion of one of said opposite planar
surfaces or said second plate with each of said cavities of said
first plate, the second plate providing a planar side wall for such
at said cavities of said first plate.
6. The method of claim 1 wherein said step of manipulating a
relative position of a metal-cutting beam of a laser with respect
to said first plate to cut a cavity comprises cutting completely
through the first plate, the wall of the cavity extending from the
outer surface of the first plate to an opposite outer surface of
the first plate, the method further comprising a step of
positioning a third plate adjacent said opposite outer surface of
said first plate, said second plate and said third plates defining
opposite side surfaces of each of the cavities.
7. The method of claim 1 in which the series of mold cavities is
arranged on a circular periphery to define a mold ring.
8. The method of claim 1 wherein manipulating a relative position
.[.or.]. .Iadd.of .Iaddend.a material-cutting beam comprises moving
the material cutting beam.
9. The method of claim 1 further comprising assembling a plurality
of said first and second mold plates in a stack-form to a mold with
an exposed outer surface comprising said peripheral edge surface of
each mold ring and said series of cavities extending inwardly
therefrom.
10. The method of claim 9, wherein said step of assembling said
mold plates in a stack-form to provide a molding apparatus further
comprises providing an alignment shell defining a circular aligning
surface, and at least one aligning bar; and arranging the plates in
said stack-form with each plate being supported on an outer
circumferential surface by said aligning surface, said aligning bar
extending through an aligning hole in each mold plate.
11. The method of claim 10, wherein said step of assembling further
comprises axially compressing said stack of plates to maintain the
radial alignment provided by said circular aligning surface.
12. The method of claim 11, wherein said step of assembling further
comprises removing said aligned stack of rings from said alignment
shell.
13. The method of claim 1, wherein said step of manipulating a
relative position of a material-cutting beam of a laser includes
laser-cutting the outer edges of said mold plates.
14. The method of claim 1, wherein said first plate is between
0.006 to 0.020 inch thick.
15. The method of claim 1, wherein said first plate and said second
plate each include a coolant passage, said step of positioning
including aligning said coolant passage of the first plate with
said coolant passage of said second plate.
16. The method of claim 15, wherein said step of manipulating a
relative position of a material-cutting beam of a laser comprises
laser cutting said coolant passages.
17. The method of claim 1, wherein said laser is maneuverable by an
articulating arm that provides movement about a five-axis
orientation relative to said first plate.
18. The method of claim 1, wherein said first plate is fixed to an
articulating table that provides five-axis motion relative to said
laser.
19. The method of claim 1, wherein said first plate is fixed to an
articulating table and both said laser and said articulating table
are maneuverable so that, in combination, they provide relative
movement of said plate to said laser about a five-axis orientation.
Description
TECHNICAL FIELD
This invention relates to molding features that are integral with a
base, and has particular application to the production of fastener
elements for touch fasteners and the like.
BACKGROUND
Hook elements for hook-and-loop touch fasteners and other products
are effectively produced by the machine and method of Fischer U.S.
Pat. No. 4,794,028. In commercial production, a mold roll is formed
by a large number of thin, disk-shaped mold rings (sometimes called
mold plates) and spacer rings which are stacked concentrically
about a central barrel.
Discrete products are also injection molded with fastener elements
extending from a base surface by employing, as part of the mold, a
series of stacked mold plates defining an array of mold
cavities.
At the periphery of the mold rings or mold plates are cavities for
molding the hook elements. In current production machines each
cavity of a mold ring has been formed, one at a time, by wire
electro-discharge machining (EDM). In the wire EDM process, an
electrical discharge between a wire and the plate removes material
from the plate while the wire is moved along a specified path to
cut a profile through the mold plate. The minimum radius arc that
can be cut is determined by the radius of the EDM wire.
Molten resin is forced into the mold cavities, tending to raise the
temperature of the mold rings. In practice of the Fischer method, a
fluid coolant is circulated through cooling passages within the
barrel on which the rings are mounted to remove the heat from the
rings.
In this way an appropriate temperature of the mold cavities is
maintained so that the product becomes sufficiently solid that it
can be withdrawn on a continuous basis, typically without opening
the mold cavities.
SUMMARY
In one aspect, the invention provides a method of forming a mold
having cavities for molding loop-engageable, hook-shaped fastener
elements. The method includes: supporting a first plate having an
outer surface that defines a plane; manipulating a material-cutting
beam of a laser along a predetermined curved profile to cut a
cavity into the outer surface of the first plate, the predetermined
curved profile being generally hook-shaped, the cavity defined by a
wall extending into the first plate from the outer surface; in a
series of subsequent actions, repeatedly indexing the first plate
relative to the laser to direct the material-cutting beam at
further positions on the first plate and repeating the step of
manipulating the material-cutting beam of the laser relative to the
first plate to form a series of cavities, each having a hook-shaped
profile; and positioning a second plate adjacent the outer surface
of the first plate, the second plate providing a side wall surface
for each of the cavities of the first plate, the first plate and
the second plate in combination forming a mold having cavities for
molding loop-engageable, hook-shaped fastener elements.
Variations of this aspect of the invention can include one or more
of the following features. The step of manipulating a
material-cutting beam of a laser to cut a cavity includes
positioning the material-cutting beam at an acute angle relative to
the plane defined by the upper surface of the first plate to form
at least a portion of the wall defining the cavity at a
corresponding acute angle relative to the plane. The step of
manipulating the material-cutting beam of the laser to cut the
cavity includes cutting only partially through the first plate, a
remaining portion of the first plate providing a second side
surface of the cavity, opposite the side surface formed by the
second plate. The method further includes a step of forming a
series of cavities on the second plate, the cavities of the second
plate being of mirror image relative to the cavities of the first
plate, the step of positioning the second plate adjacent the outer
surface of the first plate including aligning the cavities of the
first plate with the cavities of the second plate to form a series
of hook-shaped cavities, each having one side surface formed by a
remaining portion of the second plate and an opposite side surface
formed by a remaining portion of the first plate. The second plate
has opposite planar surfaces, the method further includes a step of
forming a series of cavities extending into the second plate from
one of the opposite planar surfaces, the step of positioning the
second plate adjacent the outer surface of the first plate
including aligning a non-cavitated portion of one of the opposite
planar surfaces of the second plate with each of the cavities of
the first plate, the second plate providing a planar side wall for
each of the cavities of the first plate. The step of manipulating a
metal-cutting beam of a laser to cut a cavity includes cutting
completely through the first plate, the wall of the cavity
extending from the outer surface of the first plate to an opposite
outer surface of the first plate, the method further including a
step of positioning a third plate adjacent the opposite outer
surface of the first plate, the second plate and the third plates
defining opposite side surfaces of each of the cavities. The series
of mold cavities is arranged on a circular periphery to define a
mold ring.
In another aspect, the invention provides a method of forming a
mold plate for forming at least a portion of an adjacent series of
hook-defining mold cavities, the mold plate provided for assembly
with additional plates to form a molding apparatus for molding a
fastener member having loop-engaging hook fastener elements
extending from a base. The method includes: supporting a metal
plate to expose a planar outer surface of the metal plate;
controllably directing a metal-cutting beam of a laser along a
predetermined path to cut the metal plate to form the mold plate,
the pre-determined path requiring the metal-cutting beam to cut
completely through a portion of the metal plate to define a
peripheral edge surface of the mold plate for molding a portion of
the base of the fastener member, the predetermined path further
requiring the metal-cutting beam to cut into the planar upper
surface of the metal plate at predetermined intervals to define a
series of cavities in the mold plate for forming the
loop-engageable hook fastener elements of the fastener member, each
of the cavities being defined by a wall extending into the mold
plate from the planar upper surface and extending into the mold
plate from the peripheral edge surface.
Variations of this aspect of the invention can include one or more
of the following features. The metal-cutting beam is controllably
directed to cut the metal plate so that at least a portion of the
wall of each of the series of cavities forms an acute angle
relative to the planar outer surface. The metal-cutting beam is
controllably directed to cut the metal plate so that each of the
series of cavities is defined by a wall extending from the planar
outer surface completely through to an opposite outer surface of
the metal plate.
In another aspect, the invention provides a method of forming a
fastener member having a plurality of loop-engaging fastener
elements extending from a base. The method includes: (a) providing
a metal plate having a planar surface; (b) cutting the metal plate
with a beam of energy from a laser to form a mold ring having a
peripheral edge surface, the beam of energy articulated in a
pre-determined manner along a curved path to form a series of
cavities in the mold ring, each cavity of the series having a wall
formed by the beam of energy that extends inwardly from the
peripheral edge surface and extends inwardly from the planar
surface of the mold ring; (c) repeating steps (a) and (b) to form a
plurality of mold rings; (d) assembling the plurality of mold rings
in a stack-form to provide a molding apparatus with an exposed
outer surface including the peripheral edge surface of each mold
ring and the series of cavities extending inwardly therefrom; (e)
introducing molten thermoplastic resin onto the exposed outer
surface of the molding apparatus and into the series of cavities,
the peripheral edge surfaces shaping the thermoplastic resin to
form a surface of the base of the fastener member, the series of
cavities shaping the thermoplastic resin to form the plurality of
loop-engaging fastener elements of the fastener member extending
from the base; and (f) removing the thermoplastic resin in an at
least partially solidified state from the molding apparatus to
provide the fastener member.
Variations of this aspect of the invention can include one or more
of the following features. The step of assembling the mold plates
further includes providing additional flat plates adjacent the mold
rings in the stack-form of the molding apparatus, the additional
flat plates forming at least one side of some of the plurality of
the loop-engaging fastener elements of the fastener member. At
least one of the mold rings has laser cut cavities that are a
mirror image of the cavities of another of the mold rings, the one
and the another of the mold rings assembled adjacent each other in
the molding apparatus so that their respective cavities mate to
form opposite sides of a loop-engaging fastener when filled with
thermoplastic resin. The step of cutting the metal plate with a
beam of energy from a laser to form a mold ring further includes
controllably directing the beam of energy of the laser to cut the
metal plate to define the peripheral edge surface of the mold ring.
The step of cutting the metal plate with a beam of energy from a
laser to form a mold ring further includes controllably directing
the beam of energy of the laser to cut the metal plate to define an
alignment hole in the mold ring. The step of assembling the mold
rings in a stack-form to provide a molding apparatus further
includes: providing an alignment shell defining a circular aligning
surface, and at least one aligning bar; and arranging the rings in
the stack-form with each ring being supported on its outer
circumferential surface by the aligning surface, the aligning bar
extending through a the aligning hole in each mold ring.
In yet another aspect, the invention provides a method of aligning
a multiplicity of thin, disk-shaped mold rings, each having an
array of aligning holes and an outer circumferential surface, to
form a mold roll. The method includes: providing an alignment shell
defining a circular aligning surface, and at least one aligning
bar; stacking the rings together to form a stack, each ring being
supported on its outer circumferential surface by the aligning
surface, with the aligning bar extending through a the aligning
hole in each ring; axially compressing the stack of rings to
maintain the radial alignment provided by the circular aligning
surface; and removing the aligned stack of rings from the alignment
shell.
Variations of this aspect of the invention can include one or more
of the following features. The mold plates are round and the step
of forming includes laser-cutting the outer edges of the mold
plates. The step of stacking includes axially stacking the round
mold plates to form a mold roll.
In another aspect, the invention provides a hook product for a hook
and loop fastening system, the hook product including a plurality
of hooks extending from a common sheet-form base. Each of the hooks
has a stem portion and a crook portion. The stem portion is
integrally molded with and extends from the sheet-form base to a
distal end, and has a planar side. The crook portion extends from
the distal end of the stem portion to overhang the sheet-form base
in an overhang direction. The crook portion has a flat planar side
coplanar with the planar side of the stem, and an upper surface
extending upward from an tipper extent of the planar side of the
crook portion to an apex.
Preferably, the upper surface extends at an angle of at least 30
degrees with respect to the base, at the uppermost region of the
crook portion.
Preferably, the flat planar side of the crook portion has a width,
at the uppermost region of the crook portion, of at least 50
percent of the overall width of the hook.
In some cases, the crook portion also includes an opposite side,
the apex being located at one of the sides of the crook
portion.
In some embodiments, the crook portion further includes a second
upper surface extending from the second side of the crook portion
to the apex, which may be located between the first and second
sides of the crook portion.
In some examples, the crook portion also has a first lower surface
that, in a cross-section taken perpendicular to the base and the
first side surface through an uppermost region of an underside of
the crook portion, extends downward from the first side surface of
the crook portion. In some cases, the crook portion also has a
second lower surface that, in the same cross-section, extends
downward from the second side surface of the crook portion to
intersect the first lower surface.
Preferably, the upper surface extends at an angle of at least 30
degrees with respect to the base, at the uppermost region of the
crook portion.
Preferably, the flat planar side of the crook portion has a width,
at the uppermost region of the crook portion, of at least 50
percent of the overall width of the hook.
The invention provides an advantageous hook product and advantages
in the design and manufacture of fastening elements and hooks of
such products by allowing great design flexibility in selecting and
producing cavity shapes for forming such fastening elements. This
design flexibility allows for the manufacture of fastening elements
that are particularly well-suited for their intended applications
because the base, stem and engaging head, or crook, design of such
fastening elements can be specifically tailored to accommodate
expected strength and/or engageability requirements, such as, for
example, those presented by low-loft, nonwoven mating loop
materials.
The invention further provides advantages in the manufacture of
fastening elements by providing greater precision and accuracy in
the construction and assembly of the various pieces that form the
molding apparatus from which such fastening elements are
manufactured. These construction and assembly advances provide for
efficiency and reliability gains in the manufacture of fastening
products.
The details of one or more embodiments of the invention are set
forth in the accompanying drawings and the description below. Other
features, objects, and advantages of the invention will be apparent
from the description and drawings, and from the claims.
DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic representation of a molding system employing
a mold roll;
FIG. 2 is a fragmentary view of a mold roll, according to the
invention;
FIG. 3 is an enlarged cross-sectional view, taken along line 3--3
in FIG. 2;
FIG. 4 is an enlarged cross-sectional view, taken along line 4--4
in FIG. 3;
FIGS. 4A through 4C are enlarged views of a preferred embodiment of
a hook feature formed by a cavity of the mold roll of FIG. 2;
FIGS. 5A through 5D illustrate preferred methods of mold ring
manufacture;
FIG. 6 illustrates a method for aligning and assembling the mold
roll;
FIG. 6A is a side view of a molded fastener element with a sharp
tip;
FIG. 6B is a front view of the fastener element of FIG. 6A;
FIG. 6C is a close-up view of area 200 of FIG. 6A;
FIG. 7A is a perspective view of a concave mold surface;
FIG. 7B is a side cross-sectional view of laser machining the mold
surface of FIG. 7A;
FIG. 8A is an edge view of adjacent mold plates forming a mold
cavity with a curved mold surface and an opposing plate side
surface;
FIG. 8B is an edge view of mold plates forming a mold cavity with
two opposing, curved mold surfaces; and
FIG. 9 is a perspective view of an injection mold showing the
orientation of a mold cavity diagrammatically.
FIG. 10 is a side view of a hook fastener element formed by a mold
ring manufactured according to the techniques illustrated in FIGS.
5C and 5D.
FIG. 10A is a front view of the hook fastener element of FIG.
10.
FIGS. 10B-10E are cross-sectional views taken along respective
lines in FIG. 10.
FIGS. 11, 11A, 11B, 12, 12A and 12B are perspective views of
alternate embodiments of hook fastener elements.
FIG. 13 is a cross-sectional view, taken along line 13--13 in FIG.
11.
FIG. 14 is a cross-sectional view, taken along line 14--14 in FIG.
12.
Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
FIGS. 1-4 illustrate equipment useful for the continuous molding of
synthetic resin to produce features that are integral with a base
sheet, having particular application to the production of fastener
elements for touch fasteners and the like.
FIG. 1 shows a molding system using the molding roll for the
production of hook elements for touch fastener products. The
process and basic machine shown are in accordance with the Fischer
techniques as described in U.S. Pat. Nos. 4,775,310, 4,794,028 and
4,872,243, which are hereby incorporated by reference as if they
were fully set forth.
The mold roll 1 has miniature hook form mold cavities around its
periphery for forming hook projections on an extruded strip-form
touch fastener product 4. Mold roll 1 comprises many annular, thin
mold rings, for instance of 0.006 to 0.020 inch thickness, held
together as a stack. Heat-softened synthetic resin 5 is forced into
the cavities under pressure. In a continuous process, the hook-form
projections at least partially solidfy in the mold cavities, and
are then pulled out of the cavities in area 8 after the product has
cooled to a temperature at which the projections have solidified
sufficiently to be pulled intact out of their mold cavities,
remaining integral with the base sheet of the product. The
projections are pulled out of mold roll 1 by passing the product
around an idler roll 44, and from there to the takeup assembly
50.
In the present invention, the individual mold rings 9 of mold roll
1 are aligned and stacked axially around a common shaft 15. Rings 9
are held together under axial compression by an array of tie rods
16 extending through aligned holes in the stack of rings, running
parallel to shaft 15 and tensioned by threaded nuts 17 at each
end.
An array of many coolant passages 22 pass through mold roll 1 near
the periphery of mold rings 9 for improved cooling of the mold
cavities at the periphery of the mold roll. In one configuration,
cooling fluid is pumped into the mold roll through an annular inlet
60 in shaft 15, and passes through shaft holes 62 and passages 64
of an inlet manifold 26. From the inlet manifold, the coolant
passes through the mold roll along cooling passages 22 to an outlet
manifold 25 at the other end of the mold roll, which also has
passages 64 to direct the coolant through shaft holes 65 and a
return passage 66 in shaft 15, to outlet 68.
Referring to FIG. 3, the mold cavities 2 near the periphery of hold
roll 1 are shaped to form fastener elements integral to a base
sheet. These mold cavities 2 form features of about 0.005 to 0.100
inch in height, and on the order of 0.005 to 0.100 inch wide. For
improved cooling, coolant holes 21 are in close proximity to mold
cavities 2, within a distance d of, for instance, 0.2 inch. Also
visible in this view is a gap 70 between tie rod 16 and the wall of
an associated hole 71 through the mold roll. This gap enables
improved mold ring alignment, as will be discussed later.
As seen in FIG. 4, in certain circumstances mold cavities 2 are
formed such that they do not extend through the entire thickness of
a mold ring 9. With the mold cavities thus formed, mold rings 9 are
stacked directly against one another, with the open surface 18 of
one ring, for instance ring 9a, against the closed surface 19 of
the next ring, for instance ring 9b, which forms a side of the mold
cavities in ring 9a.
An advantage of forming mold cavities 2 such that they do not
extend through the thickness of mold ring 9 is that they may be
used to form features with at least one curved side, formed by a
concave surface 20. The resulting tapered and convex nature of the
hooks, as shown in FIGS. 4A through 4C, can contribute to the
penetrability of the hooks into shallow loops, such as presented by
non woven fabrics. In the case of extremely small hooks in close
rows, the portion 72 of the mold ring that functions as a spacer
between rows of hooks adds thickness to the ring and makes it
easier to handle during fabrication and assembly.
In other embodiments (not shown), the mold cavities extend through
the thickness of the mold rings. In these configurations, spacer
rings void of mold cavities are stacked between mold rings to
enclose the mold cavities that are otherwise defined in the mold
rings. In yet another embodiment, mold cavities are formed on both
sides of some mold rings, the array of mold cavities on the two
sides of the ring being circumferentially offset to avoid
interference between mold cavities on mating rings. In another
preferred embodiment a mold cavity for a given feature is formed by
accurately aligned cavity portions in two or more mold rings to
form a single mold cavity.
Referring to FIG. 5A, in certain preferred embodiments a
photochemical (PC) etching process is used to form mold cavities 2,
2', coolant passages 22, and other features, such as an alignment
feature (not shown) for aligning adjacent individual mold rings 9
during assembly of mold roll 1. In the embodiment illustrated, mold
cavity 2 does not extend through the thickness of mold ring 9,
while mold cavity 2' does. In the ring fabrication process, an
etch-resistant photoresist material 131 is fixed to the surfaces of
a sheet 82 of mold ring material of the proper thickness and then
developed by exposure to ultraviolet light through a mask (not
shown) that is cut to produce the desired final surface
configuration, including preferably the finished inner and outer
diameters of the mold ring. The undeveloped photoresist material in
areas beneath the mask remains fixed to the sheet as the developed
material 131 is removed. Etching fluid 32 is then sprayed on the
surfaces of the sheet, etching the areas not covered by
etch-resistant material 131. When the etching process is complete,
material 131 is removed from the finished mold ring 9. As a natural
result of the PC etching process the etching rate is slower at the
bottom of the mold cavity, due in part to the dilution of the
etching fluid, thus creating a concave surface 20 at the bottom of
molding cavity 2, and useful undercuts (not shown) in some
arrangements.
In other preferred embodiments, especially those involving large
hook elements and other features, the mold cavities are formed with
PC techniques by etching through the thickness of the sheet, e.g.,
as illustrated by cavity 2' of FIG. 5A, either from one side or by
etching through both sides.
An advantage of the PC process is that all of the features on a
mold ring 9, including the inner and outer diameters, coolant holes
21 and mold cavities 2, 2' can be advantageously produced at the
same time or in an appropriate sequence, using precisely positioned
masks in accordance with general photo-lithographic techniques, as
employed e.g., in the semiconductor industry. In some cases, for
instance, one side of a sheet of mold ring stock is appropriately
masked to etch all of the features to the depth of the mold
cavities 2, and the other side of the sheet is masked by a system
that holds registration to complete the etching of the inner and
outer diameters and coolant holes 21 through the thickness of mold
ring 9.
Referring to FIG. 5B, a laser machining technique is employed in
other embodiments to produce mold rings 9 from a sheet 33 of ring
stock. Using the laser machining process, hook profiles cut through
the thickness of sheet 33 are readily formed, and these can be
advantageously of smaller size than those previously formed using
wire EDM methods. For instance, hook elements as short as 0.005 to
0.008 inch, with appropriately small radii of 0.001 or 0.002 inch,
can be formed. To produce a mold ring by the laser machining
process, sheet 33 of the proper thickness is fixtured to be
presented to a laser head 34. A beam 35 of energy from laser head
34 removes material from sheet 33, according to a programmed
pattern, to produce a finished mold ring. Head 34 is typically
mounted on a positionable base, such that the motion of the head
can be controlled as desired to form the features of the finished
ring. Transverse X-Y motion of a table carrying sheet 33 may also
be employed. The depth of the groove produced by the effect of the
beam 35 on the sheet 33 is a function of the intensity or power of
the beam 35, the material properties of the sheet 33, and the speed
at which the head 34 or sheet 33 is moved. Varying these parameters
can produce the desired depth of the mold cavities, while also
cutting through the entire thickness of the sheet to form the
coolant holes 21, the holes 71 for the tie rods, and the ring inner
and outer diameters. In the case where a through-cut is not
desired, particularly close control of the deposition of laser
energy is maintained to limit the vaporization of the ring material
to produce, for example, the general cavity shape of FIGS. 4A, 4B
and 4C.
In another embodiment, illustrated in FIG. 5C, laser head 234 is
maneuverable by an articulating arm that provides movement about a
five-axis (X, Y, Z, A1, A2) orientation of cutting laser beam 231
relative to sheet 236. Movement of head 234 is controlled by a
programmable computer (not shown) that positions the head relative
to sheet 236 so that emitted beam 231 vaporizes portions of sheet
236 in a controlled manner to produce, e.g., mold ring 238. In an
alternative embodiment, laser head 234 is held still while sheet
236 is fixed to an articulating table 237 that provides five-axis
(X', Y', Z', A1', A2') motion of sheet 236 relative to laser head
234. In yet other embodiments, both head 234 and sheet fixturing
table 237 are maneuverable so that, in combination, they provide
relative movement of sheet 236 to head 234 about a five-axis
orientation.
Programmable articulation of head 234 relative to sheet 236 allows
for great design flexibility in choosing the shape of a
hook-forming cavity 240 formed by emitted beam 231. Particularly,
the angle of beam 231 relative to sheet 236 is manipulable to form
mold ring features such as peripheral edges, coolant passages, ring
alignment holes or features, and/or hook forming cavities having
walls angled relative to a plane defined by outer side surface 242
of ring sheet stock 236. Moreover, as illustrated in FIG. 5D, the
amount of any such angle can be varied along the path of
vaporization of mold ring stock 236. For example, mold ring 238 has
a peripheral edge surface 244 that forms a substantially
perpendicular angle, .alpha.1, with side surface 242, while cavity
246 has a hook base-forming portion 248 with an acute cavity wall
angle, .alpha.2, relative to side surface 242 and a hook
tip-forming portion 249 with an even more acute wall angle,
.alpha.3 relative to side surface 242. Hook forming cavities having
variably angled walls provide advantageous hook shapes as
illustrated in FIGS. 10 through 12 and further described below.
Referring to FIG. 6, the structure of the mold roll according to
the invention enables an improved mold ring alignment method, using
a radial alignment shell 36 and one or more orientation bars 37.
Preferably, the rings are sequentially stacked about shaft 15 which
is concentrically aligned to shell 36 by the inlet and outlet
manifolds (i.e., 25) or other means. Tie rods 16 (or other
alignment bars inserted through holes 71) align holes 71 as rings 9
are stacked, also aligning coolant holes 21 in each ring to form
the cooling passages of the assembled roll. Particularly useful in
the assembly of a mold roll for the production of fastener products
with good base thickness consistency, the inner surface 37 of shell
36 aligns the outer surface of the rings, such that the assembled
roll has a very cylindrical circumference for producing an even
base thickness in the molded fastener product. In addition, the
stack of rings is concentrically aligned with shaft 15. The gap
(70, FIG. 4) between tie rods 16 and the inner edges of holes 71
enables each ring to be radially aligned by surface 37 of shell 36
without radial restraint from tie rods 16. After rings 9 are
stacked, the other manifold is set in place and the stack 38 is
compressed and removed from alignment shell 36.
In an alternative embodiment (not shown), the rings are aligned
with an expandable center shaft.
In molding machines that employ substantially the Fischer process,
other systems from that shown in FIG. 1 may introduce pressurized
heat softened or molten synthetic resin to the surface of the mold
roll under conditions that fill the mold cavities and form a base
layer integral with features molded in the cavities. For instance
an extruder may be moved closer to the roll from what is shown in
FIG. 1 and the extruder nozzle may confine the resin so that it is
applied with pressure directly to the mold roll, filling the
cavities and forming a base layer of desired thickness. In such a
configuration, the structure of the mold roll of the invention can
advantageously stiffen and align the roll for improved base
thickness consistency, enabling the production of thinner bases,
and wider products.
Shown in FIGS. 6A and 6B is a fine, sharp tip fastener element
formed with mold plates fabricated by the laser machining process
illustrated in FIG. 5B. Elements with tips having radii, R (FIG.
6C) of about 0.001 inch or less (preferably only about 0.0005
inch), are obtainable with laser-machined molds. Certain advantages
are provided by sharp tip fastener elements including penetrability
into the loops of engaging loop materials. The sharp tip enables
penetration between an engageable loop and the rest of the loop
mass of a looped fastener member. Improving the loop-engaging
probability of an individual hook of a hook fastener member
increases the engagement ratio of an array of hooks, that is, the
overall percentage of hooks of the array that, at any given time,
engage loops. Higher engagement ratios typically result in better
fastener performance.
As illustrated in FIG. 7A, the laser machining process enables the
formation of mold surfaces 20 that do not extend through the entire
thickness of mold plate 9.
An advantage of forming mold surfaces that do not extend through
the mold plate is that they may be used to form fastener elements
with at least one convex surface which may contribute to the
penetrability of the elements into shallow loops, such as those
presented by non-woven fabrics. In this case, particularly close
control of the deposition of laser energy is maintained by
appropriate machine controls to limit the vaporization of the plate
material to produce, for example, the concave mold surface 20 shown
in FIGS. 7A and 7B.
Referring to FIG. 7B, the depth of the laser cut produced by the
effect of beam 35 on sheet 33 is a function of the intensity or
power of beam 35, the material properties of sheet 33, and the
speed at which the laser head or sheet 33 is moved. Varying these
parameters can produce either a concave mold surface of a desired
depth (FIG. 7A) or can cut through the entire thickness of the
sheet to form mold cavities and/or cooling holes or plate inner and
outer diameters. During laser machining of mold surfaces, hot
molten debris 106 of plate material is produced. A blower 108 is
employed to maintain an air flow 105 sufficient to continually
displace debris 106 from the forming area in the general direction
indicated by arrow 102. This is especially important when forming
concave surfaces not extending through the plate, as in FIG.
7B.
Fastener elements formed with these laser machined surfaces smaller
than those previously formed with mold surfaces produced by wire
EDM methods. For instance, small fastener elements having an
overall height of 0.020 inch, or even smaller elements, for
example, having a height of the order of 0.008 inch, are readily
produced with cavities formed by this method. Such small hooks can
be used for engaging loop materials with low-lying loops as found
in non-woven fabrics.
FIG. 8A shows a mold cavity 90 formed by stacking a mold plate 9a
with the laser machined surface 20 of FIG. 7A against the flat side
of a spacer plate 9b. Similar cavities are also formed by stacking
mold plates 9a' and 9a'' together, such that their mold surfaces 20
do not overlap. This arrangement can be used to produce fastener
products with particularly high densities.
In the embodiment shown in FIG. 8B, a mold cavity for a given
feature is formed by accurately aligned and cooperating mold
surfaces 118 and 120 in two adjacent mold plates 9c and 9d,
respectively, to form a single mold cavity 114.
In FIG. 9, the hook-forming portion of an injection mold 130 for
delivering moldable resin to the mold cavities is diagrammatically
shown. The moldable resin is injected into adjacent mold cavities
127, thereby forming the fastener elements by injection molding.
The injection mold is formed of a series of plates 122 disposed
face-to-face to create a flat (or curved) surface 123 having mold
cavities. The mold cavities can be formed in one or more plates.
After molding, the overall mold opens, the hooks are withdrawn from
the mold cavities as the molded piece is removed, and the overall
mold closes for another injection cycle. Injection molding can be
employed to form the hook members directly on a rigid backing
which, in turn, can be attached to a separate part. Injection
molding can also be employed to form the hook members integrally
with a part, such that the hook members do not need to be later
attached to the part.
As illustrated in FIGS. 10 through 10D, the laser machining
techniques described above with particular reference to FIGS. 5C
and 5D can be employed to produce fastener shapes with complex,
multi-angled surfaces. In particular, hook 250 has a diamond shaped
cross-section that tapers in longitudinal thickness from a stem
portion 251 having a relatively thick base (FIG. 10B) with a
longitudinal thickness, T1, to a crook portion 252 having a
relatively thin hook tip (FIG. 10E) having a longitudinal
thickness, T2. Crook portion 252 extends from distal end 284 of
stem portion 251 to overhang base 257, thereby defining an overhang
direction (indicated by arrow A in FIG. 10). Stem portion 251 has
opposite, parallel, planar sides 253, 254 and the crook portion 252
has opposite, parallel, planar sides 255, 256. The first sides 253,
255 of the stem and crook portions are co-planar, as are the second
sides 254, 256. As further illustrated by the intermediate
cross-section of FIG. 10C, the outer surface transitions smoothly
from its thick base to its thin tip.
Referring specifically to FIG. 10D, which illustrates a
cross-section of hook 250 taken in a plane perpendicular to both
the side 255 of crook portion and the base 257 through an upper
most region of crook portion 252, upper surfaces 258, 259 extend
upwardly from sides 255, 256, respectively, of crook portion 252 to
form an apex 280 while lower surfaces 281, 282 extend downwardly
from sides 255, 256, respectively, and intersect with one another
to form an underside 283 of crook portion 252.
Hook 250, and other such tapered hooks with angled outer surfaces
can be produced, for example, by the techniques illustrated in
FIGS. 5C and 5D. Briefly, two mold plates are laser machined so
that a partial hook-forming cavity of one mirrors a partial
hook-forming cavity of the other. The two mold plates are then
placed adjacent one another with their mirror image cavities mating
as described above with reference to FIG. 8B, the mating cavities
combining to form a single hook-forming cavity.
Alternatively, as illustrated in FIGS. 11, 11A and 11B, a
non-symmetrical, hook having angled surfaces is formed by a process
similar to that described above with reference to FIG. 8A. A mold
ring for forming the hook is made by cutting, e.g., with the angled
laser approach of FIGS. 5C and 5D, a hook-forming cavity into a
single mold ring. The mold ring is then fixtured to partially form
a molding roll, such as, for example, roll 1 of FIG. 2, so that the
hook-forming cavity of the mold ring is bounded by a flat surface
of an adjacent ring or plate. The result is, for example, a
multi-headed hook 260 (FIG. 11) having a stem portion 262 with
opposite, planar sides 263, 265 and a crook portion 264 also with
opposite, planar sides 267, 269. An angled surface 261 extends
between sides 263 and 265 of stem portion 262 and between sides 267
and 269 of crook portion 264 along the entire height of hook 260
and defines an underside 272 of crook portion 264. Meanwhile, an
upper angled surface 274 extends between sides 267 and 269 of crook
portion 264 to an apex 270 of hook 260. The crook portion 264 thus
has a flat planar side 267 co-planar with the planar side 263 of
the stem portion 262, and an upper surface 274 extending upward
from an upper extent of planar side 267 to apex 270, as shown in
FIG. 13, with apex 270 being located at side 269 of the crook
portion 264.
FIG. 13 also illustrates that crook portion 264 has a lower surface
272 that, in this cross-section taken perpendicular to the base and
the first side surface through an uppermost region of underside
272, extends downward from side surface 267 of the crook portion.
As shown in FIG. 13, the width "t" of planar side surface 267 is
significant in comparison with (e.g., at least 50% of) the overall
width "w" of the fastener element. In some cases, the width of the
planar sides of the crook portion is about the same as the width of
the fastener element. Upper surface 274 extends upward at a
significant angle .theta. with respect to the base, such as at
least about 30 degrees.
As another example, a mold ring is, e.g., laser cut to form a
multi-headed hook 260' (FIG. 11A) having an angled surface 261'
extending along the crook portion 264' from its tip down to the
distal end of 263' of the base portion 262', but the base portion
itself has a straight-surface connecting its planar sides, i.e.,
base portion 262' is defined by side 266' (and an opposite side
surface) and opposite edge surfaces 268' (one shown), sides 266'
being substantially parallel to and edge surfaces 268' being
substantially perpendicular to the broad surface (e.g., surface 242
of FIGS. 5C and 5D) of the mold ring from which hook 260' is
formed. In yet another embodiment, a mold ring is, e.g., laser cut
to form a multi-headed hook 260'' (FIG. 11B) having an angled
surface 261'' extending only along tip portion 264'', while base
portion 262'' and intermediate portion 263'' are defined by
substantially straight surfaces.
Other complex shapes with varying angled surfaces are also
possible. For example, as illustrated in FIGS. 12, 12A and 12B,
multi-headed fastener elements having angled surfaces extending
along various portions, e.g., the entire height of hook 300 (FIG.
12), the tip and intermediate portions only of hook 300' (FIG.
12A), and the tip portion only of hook 300'' (FIG. 12B), are
possible. Again, the angled surfaces of the hook are acutely angled
relevant to a plane defined by the flat surface of the forming mold
ring or plates. In this case, the crook portion 302 also has a
second upper surface 304 extending from the second side of the
crook portion to apex 270, such that apex 270 is located between
the two planar, parallel sides 267 and 306 of the crook portion, as
shown in FIG. 14.
FIG. 14 also illustrates that the crook portion 302 also has a
second lower surface 308 that, in this cross-section taken
perpendicular to the base and side surface 267 through an uppermost
region of underside 308 of the crook portion, extends downward from
side surface 306 of the crook portion to intersect lower surface
272.
The ability to shape hook-forming cavities with complex angled
walls that transition in angle and depth along the path of the
cavity provides distinct advantages. For example, having a tapered,
angled-surfaced hook tip allows the tip of the hook to engage loop
elements of relatively low loft, e.g., certain nonwoven loop
materials. Simultaneously, it is advantageous to have a relatively
thicker hook base and hook neck portion to provide overall hook
strength and durability, and to provide hook resistance to
disengagement of engaged loop fibers. The ability to cut
hook-forming cavities of complex shape by using laser-machining
techniques allows the hook designer to tailor the hook shape to the
particular requirements of a given application. Further, the
computer-controlled laser cutting of mold plate cavities provides
an accurate, repeatable process for producing fastener member
tooling.
The moldable resin may be any moldable plastic material depending
upon the intended application for the fastener element. Currently,
polypropylene is preferred. Nylon, polyesters, polyethylene,
propylene, polyethylene and copolymers thereof, or other
thermoplastic resins, may also be used.
With laser machining methods, mold surfaces can be cut through the
thickness of a mold plate at speeds of up to one circumferential
inch per minute. A finished mold plate can typically be machined in
less than one hour. In applications when close control of the
cavity surface depth is desired, a pulsed laser is preferred.
To provide very smooth surface finishes on laser-machined mold
surfaces, such that the solidified hooks are more readily released,
the laser-machined mold plates are immersed in a chemical etchant
which preferentially removes mold plate material of the microscopic
asperities left by the laser-machining process. Finished mold
surfaces with a roughness of 63 microinches, for instance, have
been found to acceptably release molded fastener elements.
The embodiments are within the scope of the claims. For instance,
mold surfaces can be formed on both sides of some mold plates, the
array of mold cavities on the two sides of the plate being
circumferentially offset to avoid interference between mold
cavities on mating plates. Multiple mold plate blanks can also be
stacked together, with features extending through the thickness of
the plates laser-machined simultaneously through all stacked
plates. These and other features and advantages will be understood
from the following claims, taken in conjunction with the foregoing
specification and accompanying drawings.
A number of embodiments of the invention have been described.
Nevertheless, it will be understood that various modifications may
be made without departing from the spirit and scope of the
invention. For example, individual mold rings can be formed using
any combination of the EDM, photochemical etching, and laser
machining techniques disclosed herein. Accordingly, other
embodiments are within the scope of the following claims.
* * * * *