U.S. patent application number 10/727725 was filed with the patent office on 2004-07-22 for custom fitted helmet and method of making the same.
Invention is credited to Moore, Dan T. III, Novak, Kathleen M..
Application Number | 20040139531 10/727725 |
Document ID | / |
Family ID | 32507866 |
Filed Date | 2004-07-22 |
United States Patent
Application |
20040139531 |
Kind Code |
A1 |
Moore, Dan T. III ; et
al. |
July 22, 2004 |
Custom fitted helmet and method of making the same
Abstract
A helmet that is custom-fitted to a wearer's head, and a method
of making the helmet, are provided. The method includes the steps
of positioning a shape-forming means over the wearer's head, and
hardening the shape-forming means to provide a hardened headform
that substantially conforms to the shape of the wearer's head. The
shape-forming means can be a stretchable beanie cap that is coated
or impregnated with a curable polymeric material, a heat-softenable
plastic sheet, or a strip or plurality of strips of curable tape
that are wrapped about the wearer's head to provide a headwrap.
Once the hardened headform has been made, it can be used to cast a
hardened plaster fixture for use as the "male" member in a mold for
casting an energy absorbing foam liner for a helmet which has an
inner surface substantially conforming to the shape of the wearer's
head. Alternatively, the hardened headform can itself be used as
the "male" member of the liner casting mold.
Inventors: |
Moore, Dan T. III;
(Cleveland Heights, OH) ; Novak, Kathleen M.;
(Cleveland, OH) |
Correspondence
Address: |
PEARNE & GORDON LLP
1801 EAST 9TH STREET
SUITE 1200
CLEVELAND
OH
44114-3108
US
|
Family ID: |
32507866 |
Appl. No.: |
10/727725 |
Filed: |
December 4, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60432193 |
Dec 6, 2002 |
|
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|
Current U.S.
Class: |
2/411 ;
2/410 |
Current CPC
Class: |
B29C 44/1204 20130101;
B29C 33/3857 20130101; B29K 2105/0809 20130101; B29L 2031/4821
20130101; A42C 2/007 20130101; B29K 2105/0836 20130101; A42B 3/12
20130101; B29C 2033/3871 20130101; B29C 33/3878 20130101 |
Class at
Publication: |
002/411 ;
002/410 |
International
Class: |
A42B 003/00 |
Claims
What is claimed is:
1. A method of making a helmet that is custom-fitted to a wearer's
head comprising positioning a shape-forming means over said
wearer's head, and hardening said shape-forming means to provide a
hardened headform that substantially conforms to the shape of said
wearer's head.
2. A method according to claim 1, further comprising using said
hardened headform to mold, or to prepare a mold for, an impact
energy absorbing liner for said helmet, said energy absorbing liner
thereby having an inner surface substantially conforming to the
shape of said wearer's head.
3. A method according to claim 2, said impact energy absorbing
liner comprising viscoelastic flexible foam.
4. A method according to claim 2, said impact energy absorbing
liner comprising expanded polystyrene.
5. A method according to claim 2, said impact energy absorbing
liner comprising expanded polypropylene.
6. A method according to claim 1, further comprising the steps of:
casting a hardened fixture within a cavity defined by said
headform, said hardened fixture substantially conforming to the
shape of said wearer's head, and using said hardened fixture to
mold an impact energy absorbing liner for said helmet, said energy
absorbing liner thereby having an inner surface substantially
conforming to the shape of said wearer's head.
7. A method according to claim 6, said impact energy absorbing
liner comprising viscoelastic flexible foam.
8. A method according to claim 6, said impact energy absorbing
liner comprising expanded polystyrene.
9. A method according to claim 1, further comprising providing a
barrier over said wearer's head prior to positioning said
shape-forming means thereover.
10. A method according to claim 1, further comprising positioning
said hardened headform adjacent a mold cavity such that an exterior
surface of said hardened headform and an interior surface of said
mold cavity define a molding space therebetween.
11. A method according to claim 10, further comprising providing a
foaming composition in said molding space, and curing said foaming
composition to provide an energy absorbing foam liner for said
helmet, said energy absorbing foam liner thereby having an inner
surface substantially conforming to the shape of said wearer's
head.
12. A method according to claim 11, said energy absorbing foam
liner comprising viscoelastic flexible form.
13. A method according to claim 11, said energy absorbing foam
liner comprising expanded polystyrene.
14. A method according to claim 6, further comprising positioning
said hardened fixture adjacent a mold cavity such that an exterior
surface of said hardened fixture and an interior surface of said
mold cavity define a molding space therebetween.
15. A method according to claim 14, further comprising providing a
foaming composition in said molding space, and curing said foaming
composition to provide an energy absorbing foam liner for said
helmet, said energy absorbing foam liner having an inner surface
substantially conforming to the shape of said wearer's head.
16. A method according to claim 11, said foaming composition
comprising isocyanate and at least one polyol.
17. A method according to claim 15, said foaming composition
comprising isocyanate and at least one polyol.
18. A method according to claim 1, further comprising providing a
hood having a hood thickness over said wearer's head prior to
positioning said shape-forming means thereover, said hood thickness
defining a clearance to accommodate a foam spacer for air
circulation which is to be provided in said helmet between an
energy absorbing liner molded using said headform and said wearer's
head.
19. A method according to claim 1, said shape-forming means being a
heat-softenable plastic sheet that is heated and positioned over
said wearer's head in a softened state, and is maintained in place
over said wearer's head until said heat-softened plastic sheet
hardens to yield said hardened headform substantially conforming to
the shape of said wearer's head.
20. A method according to claim 19, said heat-softened plastic
sheet being provided in the form of a crude flower having at least
3 elements.
21. A method according to claim 20, at least one of said elements
having a laterally extending tab, the laterally extending tab being
pressed against an adjacent one of said elements of the plastic
sheet to aid in defining the shape thereof to conform to the
wearer's head.
22. A method according to claim 1, said shape-forming means being a
stretchable beanie cap that is coated or impregnated with a curable
polymeric material, and is positioned and maintained snugly over
said wearer's head until the curable polymeric material cures to
yield said hardened headform substantially conforming to the shape
of said wearer's head.
23. A method according to claim 22, said curable polymeric material
being in the form of a curable liquid resin.
24. A method according to claim 22, said curable polymeric material
being water curable.
25. A method according to claim 22, said beanie cap being a knitted
polyester fabric that is impregnated with a water curable
polyurethane resin.
26. A method according to claim 1, said shape-forming means being
at least one strip of curable tape that is wrapped about said
wearer's head to provide a headwrap made from said curable tape
that substantially conforms to the shape of said wearer's head,
said headwrap being cured to yield said hardened headform
substantially conforming to the shape of said wearer's head.
27. A method according to claim 26, said shape-forming means being
a plurality of strips of said curable tape.
28. A method according to claim 26, said curable tape being made
from a textile material that has been coated or impregnated with a
curable polymeric material.
29. A method according to claim 26, said curable tape being made
from a curable polymeric material.
30. A method according to claim 29, said curable tape being water
curable.
31. A method according to claim 28, said curable polymeric material
being water curable.
32. A method according to claim 26, said curable tape being made
from a fiberglass fabric that has been coated or impregnated with a
curable polymeric material.
33. A method according to claim 32, said curable polymeric material
being water curable.
34. A method according to claim 6, said hardened fixture being made
from Plaster of Paris.
35. A method according to claim 19, further comprising molding an
impact energy absorbing liner using said hardened headform such
that said energy absorbing liner has an inner surface substantially
conforming to the shape of said wearer's head.
36. A method according to claim 22, further comprising molding an
impact energy absorbing liner using said hardened headform such
that said energy absorbing liner has an inner surface substantially
conforming to the shape of said wearer's head.
37. A method according to claim 26, further comprising molding an
impact energy absorbing liner using said hardened headform such
that said energy absorbing liner has an inner surface substantially
conforming to the shape of said wearer's head.
38. A method according to claim 19, further comprising the steps
of: casting a hardened fixture within a cavity defined by said
headform, said hardened fixture substantially conforming to the
shape of said wearer's head, and using said hardened fixture to
mold an impact energy absorbing liner for said helmet, said energy
absorbing liner thereby having an inner surface substantially
conforming to the shape of said wearer's head.
39. A method according to claim 22, further comprising the steps
of: casting a hardened fixture within a cavity defined by said
headform, said hardened fixture substantially conforming to the
shape of said wearer's head, and using said hardened fixture to
mold an impact energy absorbing liner for said helmet, said energy
absorbing liner thereby having an inner surface substantially
conforming to the shape of said wearer's head.
40. A method according to claim 26, further comprising the steps
of: casting a hardened fixture within a cavity defined by said
headform, said hardened fixture substantially conforming to the
shape of said wearer's head, and using said hardened fixture to
mold an impact energy absorbing liner for said helmet, said energy
absorbing liner thereby having an inner surface substantially
conforming to the shape of said wearer's head.
41. A method according to claim 1, said helmet being a motorcycle
helmet.
42. A helmet that is custom fitted to a particular wearer's head,
the helmet comprising an impact energy absorbing liner, said energy
absorbing liner being custom made such that it has an inner surface
substantially conforming to the shape of said wearer's head.
43. A helmet according to claim 42, said energy absorbing liner
being a one-piece liner.
44. A helmet according to claim 43, said one-piece liner being
substantially uniformly and continuously fitted with said wearer's
head along said inner surface thereof when said wearer is wearing
said helmet.
45. A helmet according to claim 42, said impact energy absorbing
liner being made as one piece.
46. A helmet according to claim 42, said energy absorbing liner
comprising viscoelastic flexible foam.
47. A helmet according to claim 42, said energy absorbing liner
comprising semi-rigid viscoelastic flexible foam.
48. A helmet according to claim 42, said energy absorbing liner
comprising expanded polystyrene.
49. A helmet according to claim 42, said energy absorbing liner
comprising expanded polypropylene.
50. A helmet according to claim 47, said foam exhibiting
substantially 100% crush recovery following an impact.
51. A helmet according to claim 47, said foam being effective to
attenuate the force of impact resulting from an impact velocity
anywhere in the range of 2-7 m/sec, and to dissipate a substantial
portion of said impact force away from a localized region of
impact.
52. A helmet according to claim 9, said barrier being effective to
cover the wearer's eyes, nose, and a substantial portion of the
wearer's neck.
53. A kit for making a hardened headform, the kit comprising a
resin-impregnated beanie cap and a protective barrier to shield a
wearer's head from said resin, said barrier being made from latex
or silicone.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application Serial No. 60/432,193 filed on Dec. 6, 2002,
which provisional patent application is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a method of making a custom fitted
helmet. More particularly, it relates to a method for making a
custom fitted helmet having an impact energy absorbing liner having
an inner surface that substantially conforms to the shape of the
wearer's head.
[0004] 2. Description of Related Art
[0005] Helmets having an impact energy absorbing liner are known
for all sorts of applications, including cycling, football and
other contact sports, medical intervention for persons prone to
seizures, industrial protection such as for manufacturing and
construction workers, military and other aircraft pilot protection,
etc. In all of these applications, the impact energy absorbing
liner is designed to absorb and/or dissipate energy from an impact
to the outer shell of the helmet before it is transmitted to the
wearer's head. In this manner the wearer's head is at least
partially shielded or protected from what otherwise would be the
full impact force resulting from the impact.
[0006] Conventionally, helmets are supplied in a plurality of
standard sizes, e.g., large, medium, small. Sometimes the standard
sizes are based on average head circumference, e.g. 14, 14.5, 15,
15.5, 16, inches, etc. A problem with this method of sizing helmets
is that the helmets are sized based on universal standards that are
not specific to any individual who will actually wear and depend on
the helmet for head protection. While a standard sized helmet may
provide adequate protection in some instances, it is not fitted to
the unique shape and contour of the particular wearer's head, and
therefore is prone to fit too tightly in certain aspects or along
certain locations of the head while fitting too loosely in others.
A too loosely fitting helmet can be as or nearly as catastrophic
during an impact as wearing no helmet at all, because the initial
impact against the outer helmet shell can be transferred to the
head during a second impact between the head and the loosely
fitting interior surface of the helmet. Whereas a too tightly
fitting helmet is uncomfortable to the wearer and can actually
cause traumatic injury.
[0007] Currently, "off-the-shelf" helmets are fitted so that they
fit snugly in the tightest dimension of the head--this could be
from front to back, or it could be from side to side. The other
dimension (front to back or side to side) is then looser--often
with a gap of 1/2 inch or more on each side. This gap is often
filled with non-energy-absorbing foam. As an example, a high
performance ski helmet typically has approximately 1 inch of
energy-absorbing polymer. The 1/2 inch of unused space on each side
of the helmet comes at a high price from an energy absorbing
standpoint, because even at moderate impact speeds (e.g. 6 m/s)
that extra 1/2 inch of energy-absorbing foam would result in about
a 30% improvement in g-force attenuation prior to reaching the
wearer's head. At higher speed impacts the improvement would
generally be higher due to the fact that thinner foam will `bottom`
out sooner as impact speed increases.
[0008] For these reasons, it is important and desirable that the
inner surface of the helmet fit as uniformly and snugly as possible
about the shape and contour of the individual wearer's head,
without being so tight as to result in discomfort or injury.
Conventional methods of making a custom fitted helmet include
providing a preformed elastomer sack on the inner surface of a
helmet shell, and then placing this assembly over a wearer's head
with a shell cap placed in between the head and the elastomer sack.
The purpose of the shell cap is to approximate the thickness of a
subsequently-applied impact absorbing liner and to ensure there is
sufficient space for such a liner between the elastomer sack (once
rigidized) and the wearer's head within the helmet shell. In this
method, the part of the helmet that actually will contact the
wearer's head is not custom fitted to the head, therefore this
helmet is subject to similar loosely and tightly fitting regions as
described above. Other methods are known where an expandable foam
is provided to expand in a pouch adjacent the wearer's forehead,
but the remainder of the head-contacting regions are not custom
fitted to the wearer's head. Further, in this method foaming is
actually performed adjacent the wearer's head which is cumbersome
to perform, and uncomfortable for the wearer.
[0009] Conventionally, helmets have been fit to a wearer's head
either by shimming the inside of the helmet using energy-absorbing
or comfort fitting foam pieces of varying thickness until the
proper fit is achieved, or by installing a series of foam pieces of
different thickness to provide a proper fit. There are two
disadvantages of these methods: 1. It is difficult when fitting a
helmet to know when you have achieved the proper fit. It is a trial
and error process that requires more training than is typically
available in retail stores. An improperly fitted helmet can lead to
serious consequences. 2. Energy-absorbing foam is more effective if
it is in one piece. The reason for this is that a significant
amount of energy is absorbed in the foam by pumping air through
foam--the larger the piece of foam, the longer the path the air
must take, and the better the energy-absorption. If the foam is in
several layers or discrete pieces, it is easier for the air to
escape and the energy-absorption properties are reduced.
[0010] Some manufacturers attempt to fit their helmets to wearer's
heads using "fitting pads" of highly compressible foam that has no
appreciable energy-absorbing capability. These fitting pads help
keep the helmet tight on the head rather than provide an additional
layer of energy-absorptive material. As will be apparent from the
above discussion, the use of any more than a minimum of
fitting-foam is a waste of critical space in a helmet that could be
used to absorb additional energy which could save a life or
eliminate a debilitating brain injury.
[0011] Still another approach is to use inflatable air bladders
that when inflated properly can provide enough pressure to hold the
helmet firmly on the head, yet not so much pressure that the helmet
fit is uncomfortable. The air bladders, however, are not energy
absorbing in the traditional sense, and again, the extra space that
they take could be used for energy-absorption.
[0012] There is a need in the art for a method of making a custom
fitted helmet that is economical and comfortable to the wearer,
where the energy absorbing liner that actually contacts the
wearer's head is snugly and uniformly fitted to the shape and
contour of the head.
SUMMARY OF THE INVENTION
[0013] A method of making a helmet that is custom-fitted to a
wearer's head is provided. The method includes the steps of
positioning a shape-forming means over the wearer's head, and
hardening the shape-forming means to provide a hardened headform
that substantially conforms to the shape of the wearer's head.
[0014] A helmet that is custom fitted to a particular wearer's head
is also provided. The helmet has an impact energy absorbing liner
which is custom made such that it has an inner surface
substantially conforming to the shape of the wearer's head.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a side view of a beanie cap for preparing a
headform that can be used to mold an energy absorbing liner for a
helmet according to the invention having an inner surface
substantially conforming to the shape and contour of a person's
head.
[0016] FIG. 2 is a side view of a person's head to which the beanie
cap of FIG. 1 has been applied and rolled down and/or stretched
over, substantially conforming to the shape and contour of the
person's head.
[0017] FIG. 3 is a side view of the person's head from FIG. 2 prior
to application of the beanie cap, and showing a barrier applied
over the person's head according to the invention, and also showing
a piece of flexible tubing attached along the centerline of the
rear of the person's head as a scissor guide.
[0018] FIG. 4 is a top plan view of a heat-softenable plastic sheet
that can applied over a person's head and used to make a headform
according to the invention for subsequently molding an energy
absorbing liner for a helmet having an inner surface substantially
conforming to the shape and contour of the person's head.
[0019] FIG. 5 is a top plan view of the heat-softenable plastic
sheet of FIG. 4, shown positioned atop a person's head prior to
folding the individual elements over the head to conform to the
head's shape.
[0020] FIG. 6 is a side view of the heat-softenable plastic sheet
of FIGS. 4-5, shown positioned over and substantially conforming to
the shape and contour of the person's head.
[0021] FIG. 7 is a side view of a person's head over which a
curable tape has been wrapped to provide a headform according to
the invention for subsequently molding an energy absorbing liner
for a helmet having an inner surface substantially conforming to
the shape and contour of the person's head.
[0022] FIG. 8 is a side view of a person's head having a hardened
headform substantially conforming to the shape and contour of the
person's head which was made using the beanie cap of FIGS. 1-2,
where a tight fitting elastic hood has been applied over the head
prior to application of the beanie cap to protect the person's
eyes, hair and scalp.
[0023] FIG. 9 is a schematic representation of an energy absorbing
liner forming operation where a "male" mold member is suspended
above a universally adjustable "female" mold member to define a
molding space therebetween for molding an energy absorbing liner
according to the invention.
[0024] FIG. 10 schematic side view of the "male" and "female" mold
members from FIG. 9 shown in a molding position and defining the
molding space for the energy absorbing liner therebetween.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
[0025] As used herein, when a range such as 5 to 25 (or 5-25) is
given, this means preferably at least 5 and, separately and
independently, preferably not more than 25.
[0026] The method of the present invention includes first making a
headform that conforms to the shape of the wearer's head. The
headform is made by positioning or wrapping an appropriate
shape-forming means over and against the wearer's head. When the
shape-forming means is applied to the head, it is in a softened or
flexible state such that it can bend or flex or stretch to conform
to the unique contour of the individual head to which it is being
applied. Once the shape-forming means has been applied and
conformed snugly to the shape and contour of the individual's head,
it is hardened or rigidized such that it is no longer soft or
flexible, thereby yielding a hardened headform 60 that conforms or
substantially conforms to the shape and contour of the wearer's
head.
[0027] Once hardened, the headform is carefully removed from the
wearer's head so as not to break or deform the hardened headform,
except for a scissor cut which may be employed to aid removal of
the headform, as described below. This headform is then used (in a
manner described below) to mold (or to prepare a mold for) an
impact energy absorbing liner for a helmet that has an inner
surface conforming or substantially conforming to the unique shape
and contour of the head from which the hardened headform was
made.
[0028] As used herein, the shape-forming means can be a stretchable
beanie cap that is coated or impregnated with a curable polymeric
material, a heat-softenable plastic sheet, or a strip or plurality
of strips of curable tape that are wrapped about the wearer's head
to provide a headwrap. Each of these is now described in
detail.
[0029] Referring to FIG. 1, a stretchable beanie cap 10 according
to a preferred embodiment of the invention is shown. The beanie cap
10 is made from an elastic material such that it is stretchable and
recoverable. By recoverable, it is meant that if stretched from its
relaxed state, the beanie cap 10 will tend to return to its initial
shape at rest once the external stretching force has been removed
in its uncured state. This is important to ensure that the beanie
cap 10 conforms to the unique curvature and contour of a wearer's
head after it has been stretched thereover; i.e. to ensure the
beanie cap 10 is snugly and elastically retained against the shape
of the head over its entire surface of contact.
[0030] The beanie cap 10 can be made from an elastic polymeric
fabric, such as the conventional Spandex.TM. or Lycra.TM. fabrics
known in the art, alternatively glass fibers and fabrics can be
used. In a preferred embodiment, the fabric used in beanie cap 10
is a knitted polyester fabric. Typically it is either knitted or
assembled with fabric cut on the bias so the fabric has an elastic
property and can stretch so as to conform tightly to the head and
accommodate the variations in head shapes. The beanie cap 10 is
coated, preferably impregnated or saturated with a curable
polymeric material, such as a curable polymer resin, that cures to
a hardened state. In a preferred embodiment, the curable material
is a moisture or water curable polymer that cures to a hardened
state on exposure to moisture. U.S. Pat. No. 5,228,164,
incorporated herein by reference, describes a knitted fabric
material impregnated with a water curable polymer resin that is
suitable for use in making the beanie cap 10 of the present
invention. Alternatively, a suitable knitted polyester fabric
material for making the beanie cap 10 is available by Carolina
Narrow Fabric Company (Winston Salem, N.C.). The fabric is
impregnated with a water-curing urethane polymer. The water curable
polymer cures slowly when exposed to moisture in the air, or
rapidly if water is applied directly to it. Additionally, other
suitable curable polymeric materials can be used in the beanie cap
10 according to the invention, and such materials can be selected
by a person having ordinary skill in the art without undue
experimentation. For example, other light or heat curing polymer
resins can be used.
[0031] As supplied, the beanie cap 10 has a generally tubular
structure that is open at one end and terminates at the other end
in a closed, substantially dome shape portion 12 as evident from
FIG. 1. Most preferably, the beanie cap 10 has a continuous knitted
structure with no seams. In a preferred embodiment illustrated in
FIG. 1, the beanie cap 10 has a substantial portion of its tubular
length rolled up into a roll 14 that is disposed circumferentially
about the dome shape portion 12 of the beanie cap 10. In this
embodiment, the beanie cap 10 is easily and uniformly snugly
applied over and against a wearer's head by first aligning and
placing the dome shape portion 12 against the apex of the head, and
then with the dome shape portion 12 held in place, unrolling the
tubular portion of the beanie cap 10 from the roll 14 over the head
20 such that the beanie cap 10 extends downward from the dome shape
portion 12 against the surface of the wearer's head 20. This
process is best illustrated in FIG. 2. It will be apparent from
FIG. 2 that it is not necessary that the beanie cap 10 be unrolled
an equivalent length all the way around; i.e. it may be necessary
to unroll a portion of the beanie cap 10 to a greater extent
adjacent the rear and side portions of the head 20 than adjacent
the forehead to ensure complete and effective head shape coverage.
This is expected and intended in the present invention, and such
uneven stretching/unrolling of the beanie cap 10 is accommodated by
the elastic property of the beanie cap material as described above.
The beanie cap 10 must be unrolled or pulled down over the head
sufficiently in every direction to match the head coverage of the
energy-absorbing liner that will be molded using the headform to be
made by curing the polymer impregnated in the beanie cap 10
(described below). The location of the eyebrows, the ears, the
occipital ridge, the centerline of the head and the fore and aft
horizon of head with person looking forward preferably are marked
on the beanie cap 10.
[0032] Alternatively, the beanie cap 10 is provided having no such
roll 14, such that its tubular length is not rolled up. In this
embodiment, the beanie cap 10 is stretched over the wearer's head,
and after it is tightly fitted, a terminal portion of the tubular
length of the cap may be folded up or back on itself so as not to
cover the wearer's eyes and to facilitate removal of the hardened
headform once it is complete.
[0033] Once the beanie cap 10 is stretched snugly over the contour
of the wearer's head 20, the coated or impregnated polymeric
material of the beanie cap 10 is cured or allowed to cure to yield
a hardened headform 60 from the beanie cap, in the shape and
contour of the wearer's head 20. When the preferred water curable
resin is used, the beanie cap 10 preferably is submerged or dipped
once into warm water to initiate the curing process prior to
applying the beanie cap to the wearer's head. Additionally, hot
water can be sprayed onto the beanie cap 10 once it is applied to
the head to further accelerate curing. Water vapor or ambient
moisture also can be used but will result in a slower-rate cure,
which may be desirable in some applications, e.g. if minor
adjustments are to be made to the beanie cap against the wearer's
head as the cap is cured.
[0034] After the headform 60 has hardened, it is carefully removed
from the head and used in subsequent molding operations described
below. To remove the hardened headform it is generally necessary to
cut the headform (e.g. with scissors) adjacent the back of the head
to facilitate removal. If desired, a piece of flexible tubing 15
such as polyethylene tubing can be placed along the centerline of
the rear of the person's head as a scissor guide prior to fitting
the beanie cap 10 over the head. (FIG. 3) The tubing 15 can be held
in place by any suitable means, e.g. by strips of tape 16 as shown
in the figure. The flexible tubing 15 aids cutting the hardened
headform for removal once the curable resin has cured and hardened
without risking cutting the hair or the scalp. Therefore, the
tubing 15 extends at least partially below the terminus of the
beanie cap 10 when unrolled against the rear of the head 20. If
used, preferably the tubing 15 has an outer diameter of about or
less than 1/2 inch, preferably 1/4 inch, preferably 1/8 inch, so as
not to substantially interfere with the beanie cap 10 being snugly
fitted to the head 20. Because the tubing 15 is flexible, it can be
compressed by the beanie cap 10 thereby further reducing the
tubing's impact on the snugness of the beanie cap fit.
Alternatively, instead of plastic tubing 15, a flat piece of
flexible plastic or plastic strip can be used as a scissor guide.
When the plastic strip is used, it is affixed (i.e. taped) against
the wearer's head, preferably beginning above the occipital ridge,
such that it extends downward to just below the lower terminus of
the beanie cap 10 as applied to the head. When the plastic strip is
used, the rear side of a scissor blade is guided along its length
when making the scissor cut such that the strip protects the
wearer's head (and barrier 30 if provided) from being cut by the
scissors. Once the headform is removed, the two edges of the
scissor cut are rejoined and fastened by staples or super glue, or
other suitable fastener. As a further alternative, a zipper can be
provided in the beanie cap such that once the cap is hardened to
produce the hardened headform, the zipper is simply unzipped to
permit removal of the headform from the head.
[0035] Because the beanie cap 10 is coated or saturated with a
polymeric resin, it is desirable to place a barrier over the
wearer's head 20 prior to fitting the beanie cap 10 thereover. Such
a barrier 30 is shown schematically in FIG. 3, and can be in the
form of a plastic film or sheet that has a thickness of less than
about 2 mm, preferably less than about 1 mm or 0.5 mm. Latex films
generally are water impermeable, and so these are desired for the
barrier 30 when a water cured resin is used in the beanie cap 10 to
prevent the wearer's head and hair from getting wet with resin
and/or water. In addition, latex also is substantially impermeable
to the polymeric resins used in the invention and are also
desirable for this reason. However, the barrier also can be made
from other suitable materials, such as plastic films or even
fabrics, so long as the material used will prevent or substantially
prevent penetration of the curable resin and contact of the resin
with the wearer's head. It is not necessary that the fabric be
impermeable to the resin material; so long as it will not become
saturated with the resin in the time it takes to complete the
headform making process, the barrier 30 will provide adequate
protection for the wearer's head. Preferably, the barrier 30 will
cover the person's eyes, nose, and a substantial portion of the
neck in order to shield the person from contact with the urethane
or other resin.
[0036] Preferably, the barrier 30 has an elastic or stretchy
property so it can be snugly and tightly fit against the wearer's
head in order to minimize or prevent spacing defects between the
finished headform 60 and the wearer's head. Once the barrier 30 is
in place, the beanie cap 10 is placed over the head 20 (and over
barrier 30) and the process is completed as described above. To
protect the person being fitted from water, a smock or protective
covering should be worn. Gloves should be used when fitting the
beanie since the resin will stick to hands and can cause
irritation.
[0037] FIGS. 4-6 illustrate a heat-softenable plastic sheet 40
according to the invention as well as the method of application to
a wearer's head 20. Preferably, the plastic sheet 40 is a
heat-softening thermo-forming plastic sheet such as Polyform.TM.
available from Sammons Preston Rolyan (formerly Smith &
Nephew), Bolingbrook, Ill. Most preferably, the plastic sheet 40 is
{fraction (1/16)} inch or 1/8 inch thick, however other suitable
thicknesses may be used. As shown most clearly in FIG. 4, the
plastic sheet 40 is cut into the shape of a crude flower with
between 3 and 10 "petals" or elements 42. The crude flower shape is
designed so that the plastic sheet 40 can be fitted adjacent its
geometric center against the apex of the wearer's head 20 (see FIG.
5) with individual elements 42 folded or draped down over and
against the wearer's head (FIG. 6). In the illustrated embodiment,
four elements 42 are shown extending generally outward from the
center-most portion of the sheet 40: a frontal element 43, rear
element 44, and left and right lateral elements 45 and 46
respectively. The frontal and rear elements 43 and 44 each have a
plurality of laterally extending tabs 48 which are used to aid
fixing the sheet 40 in the shape and contour of the head 20 as will
be further described. Alternatively, other appropriate shapes for
the plastic sheet 40 can be used.
[0038] Initially, the heat-softenable plastic sheet 40 is heated
above its softening temperature, typically to 65-70.degree. C. Once
softened, the heated plastic sheet 40 is draped over the head as
described above and shown in FIGS. 5-6. To protect the forehead and
ears from the heat and to keep the plastic from sticking to the
hair, a thin bathing cap or a plastic film (barrier 30) should be
placed over the head before the heat-softened sheet 40 is applied.
The plastic sheet 40 is pressed against the head in its softened
state, e.g. by hand, and is held against the head until the plastic
cools below its softening temperature and re-hardens. Once the
plastic sheet 40 has been fitted and the individual elements 42
draped over and against the wearer's head, the laterally extending
tabs 48 from the frontal and rear elements 43 and 44 are pressed
against adjacent the lateral elements 45 and 46 to aid and define
the shape of the plastic sheet 40 conforming to the wearer's head
as the plastic cools and hardens to yield the hardened headform 60
conforming to the shape and contour of the wearer's head. If
desired, a piece of flexible tubing can be used similarly as for
the stretchable beanie cap described above as a scissor guide to
aid removal of the hardened headform.
[0039] FIG. 7 illustrate a preferred method of using a curable tape
50 to provide the hardened headform. Using curable tape to define
the head shape is more time consuming and requires a skilled
technician to apply the strip(s) of curable tape 50 properly. In
this embodiment, the curable tape 50 preferably is provided in the
form of a strip or strips of compliant material, such as fabric or
other textile material or synthetic material, that is/are coated or
impregnated with a curable polymeric material. Similar curable
materials and/or resins can be employed as in the beanie cap
embodiment. The compliant material preferably is made from glass
fabric (such as fiberglass) for optimal stiffness, and is coated or
impregnated with the curing resin. The curable tape 50 also can be
made of a knitted thick, but porous, fabric or a bias cut fabric,
including synthetic fabrics. If fabrics are used they must be thick
enough to provide "section" but porous enough to allow permeation
of the water necessary for curing when a water curable resin is
used. A tape having a width of about 3-4 inches is preferred,
noting it takes approximately 700 square inches to complete a head.
A suitable resin-impregnated complaint fabric tape is 3M
Scotchcast.TM. Plus Casting Tape (3M Health Care, St. Paul, Minn.),
which is a knitted fiberglass fabric impregnated with a
water-curable polyurethane resin. Alternatively, the curable tape
50 can be made from a strip or strips of curable polymeric
material, such as strips of yet uncured polyurethane which can be
hardened e.g. by contacting with water.
[0040] The tape 50 is wrapped around the head 20 as shown in FIG.
7, being careful to get the tape low enough so that the full
head-contacting surface for the energy-absorbing liner for the
helmet is defined. Just as in the above-described embodiments, a
barrier 30 can be and preferably is employed to prevent or minimize
contact of the resin or curing water with the wearer's hair or
scalp. In this embodiment, the barrier 30 can be used in addition
as a guide to indicate how far down on the head the tape 50 should
be applied. As with the beanie cap, gloves should be used when
applying the tape 50 and smock or a protective covering should be
worn to protect the person being fitted. In the preferred
embodiment, when the tape 50 is coated with a water curable resin,
the tape is initially squeezed or wrung in warm water to begin the
curing process, and is then wrapped quickly around the perimeter of
the head, cut, and several layers are placed over the top of the
head, so that the head is filly covered. A final wrap is made
around the head just above the initial wrap to ensure that there
are no gaps. The tape is gently wiped downward and pressed against
the head until the tape hardens. When using the preferred water
curing resin, the tape cures in less than 10 minutes when water is
applied, yielding the hardened headform 60.
[0041] Because the resin will cure (and consequently the tape will
rigidize) quickly after being immersed in water, a skilled
technician will be required to apply the tape properly before it
has rigidized. In this embodiment, a certain level of practice is
anticipated on the part of the technician to develop a sufficiently
rapid wrapping technique.
[0042] Irrespective of which of the above shape-forming means is
used to provide the hardened headform, care must be taken to cover
the proper amount of the head so that the subsequently formed
energy absorbing liner (molded from the headform, or whose mold is
made using the headform as described below) complies with the
proper coverage standards and suitably covers the appropriate
portions of the head. For example, for motorcycle helmets, the
highest coverage standard is Snell M2000 or DOT FMVSS 218, for
football helmets it is ASTM F429-01 or NOCSAE Doc. 002-96m98, and
for bicycle helmets it is ASTM F1447-99a or CPSC Prt. 1203.
[0043] Also irrespective of which of the above shape-forming means
is used to provide the hardened headform, preferably a clearance is
provided to position a thin layer of foam spacer or spacer(s) to
allow for air circulation, as well as the aesthetic lining or
upholstering material that will cover all or part of the inside
surface of the helmet. This clearance can be provided by placing a
tight fitting elastic hood 65 as seen in FIG. 8 having a hood
thickness over the head prior to applying the shape-forming means
thereover. The hood thickness preferably is approximately 1/8 to
1/4 inches. This will result in the subsequently formed impact
energy absorbing liner having a larger interior dimension,
providing the clearance for the foam spacers for air circulation.
An alternative method is to create the clearance on the "male"
member of the liner mold (described below) by covering it with wax
or stretchable material (such as silicone or latex material), or
another material with the proper thickness that will provide the
necessary clearance.
[0044] Once the hardened headform has been made using any of the
shape-forming means described above, it can itself be used as the
"male" member, together with a suitable "female" member, of a mold
for molding the impact energy absorbing liner for the helmet.
Alternatively, the hardened headform can be used as a mold cavity
(previously occupied by the wearer's head) into which plaster or
some other molding compound is poured, which will itself harden and
then will be used as the "male" member of the mold for making the
energy absorbing liner. Each of these methods is now described with
respect to FIG. 9.
[0045] In the first method, where the headform is itself used as
the "male" member 102 of the mold, the headform is positioned
adjacent and spaced a distance from the concave inner surface 104
of a "female" mold member 103 such that the exterior surface 105 of
the headform and the inner surface 104 of the "female" mold member
define a molding space 108 therebetween for molding the energy
absorbing liner. The molding space 108 will have very close to the
same dimensions as the finished impact energy absorbing liner as
will become evident. When using the hardened headform 60 as the
"male" member 102 of the mold, the exterior surface of the headform
is sanded to eliminate defects such as exterior bumps, ridges, and
wrinkles. Any holes in the headform also should be tightly taped
both inside and out so that the expanding foam will not cause them
to depress. Typically, the headform is then filled with a hardening
material and a pipe or other handle is suspended in the hardening
material until it is hardened. The pipe/handle allows the headform
to be held and articulated. A layer of stretchable plastic or
rubber may be stretched over the headform to create clearance for
inserting foam spacers for air circulation if the wearer's head was
not previously provided with an elastic hood 65 to provide such
clearance as described above.
[0046] In the second method, Plaster of Paris (preferred) or other
suitable plaster or curable/hardening material is poured or
provided in its uncured state into the cavity defined by the
hardened headform, and is then cured to provide a male fixture in
the shape of the wearer's head from which the headform was made. In
order to prepare the headform to cast the male fixture from plaster
or other suitable material, it is important first to seal the
headform with an appropriate sealant to make it water tight. If
desired, a pipe or other handle structure can be inserted into the
yet-uncured Plaster of Paris material and suspended in place until
the plaster dries to facilitate handling and fixturing. When the
plaster has cured, the hardened plaster fixture is removed from the
headform and is lightly sanded to smooth and to remove ridges and
irregularities. If the headform was hardened over the wearer's head
without the elastic 1/8 inch to 1/4 inch thick hood 65 in place
(see above and FIG. 8), it may be necessary to provide a clearance
for the foam spacers to be positioned between the energy absorbing
liner and the wearer's head in the finished helmet. A tight fitting
urethane film, or a latex or silicone cover is believed to work
effectively. In any case, the surface that is exposed to the
foaming composition (described below) should be coated with a
release coating so that the foam of the energy absorbing liner will
not stick to it once cured.
[0047] The "female" mold member 103 can be a conventional female
mold member having a cavity 110 for molding foam or other resinous
energy absorbing materials, e.g. as shown in FIG. 9. Alternatively,
the "female" mold member can be the outer helmet shell into which
the liner ultimately is to be placed. In this embodiment, the liner
is formed in situ, directly in the helmet shell and can bind to the
inner surface of the shell as it cures.
[0048] Returning to FIG. 9, a schematic representation of an energy
absorbing liner forming operation is portrayed. While this
schematic is shown having a conventional "female" mold member
having cavity 110, it will be understood that the principal of
operation as displayed and further described will not be
substantially different when liner is formed directly into the
outer helmet shell. In addition, "male" member 102 in FIG. 9
schematically portrays the male member of the mold which conforms
to the shape of the wearer's head for which the liner is being
cast, and can be either the hardened headform or a plaster fixture
made from the headform as above described. The apparatus shown in
FIG. 9 is similar to the structure of a Bridgeport milling machine,
having a table 180 that is universally adjustable to provide
precise alignment and adjustability between the "female" mold
member 103 on the table, and the "male" mold member 102 suspended
above.
[0049] To make the energy absorbing liner, the "male" member 102 is
positioned such that its exterior surface 105 is located adjacent
and spaced apart a distance from the concave inner surface 104 of
the "female" mold member 103, such that the exterior surface 105 of
the "male" member 102 and the inner surface 104 of the "female"
member 103 define a molding space 108 therebetween having a
substantially spheroid shape. To ensure uniformity of the spheroid
molding space, the "male" member 102 and mold cavity 110 can be
assembled to a press 150 as shown in FIG. 9, where the "male"
member 102 is mounted to a retractable shaft that is adapted to
centrally align the "male" member with the mold cavity 110.
Alternatively, other conventional or suitable alignment mechanisms
may be employed.
[0050] Next, a curable compound is provided or injected into the
spheroid molding space 108 to substantially fill that space, and is
cured or allowed to cure to form the desired impact energy
absorbing liner. Most preferably, the curable compound is a liquid
foam precursor composition that cures and expands to form an energy
absorbing foam.
[0051] The most preferred foam is a semi-rigid viscoelastic foam
made from a two-part foaming composition, preferably, one part
being isocyanate and the other part being a polyol or mixture of
polyols. Most preferably, the foam is Zorbium.TM. foam available
from Team Wendy, LLC in Cleveland, Ohio. Zorbium.TM. is an
energy-absorbing foam that, unlike expanded polystyrene (EPS),
exhibits substantially 100% crush recovery following an impact, yet
it is still effective to absorb low to high energy impact forces
(i.e. 2 to 4 as well as 4 to 7 m/sec, or anywhere in between) and
dissipate much of the impact energy away from the head at the
localized region of impact. Zorbium.TM. crushes more than EPS under
low speed impacts, and yet has approximately the same crush as EPS
under high speed impacts--it thus provides greater impact
protection over a wider range of impact velocities. Less
preferably, other known or conventional impact energy absorbing
foams or resins can be used, such as EPS or expanded polypropylene
(EPP), vinyl nitrile, etc. Generally, when molding EPS or EPP steam
is used to heat the precursor polystyrene/polypropylene beads. As
the beads soften the soluble hydrocarbons expand to generate the
foam. Therefore With EPS or EPP, the mold should be provided with a
number of vent holes to permit venting of the steam.
[0052] The thickness and density of the impact energy absorbing
liner (preferably made from foam, preferably Zorbium.TM. foam)
depend on a variety of factors, perhaps most importantly the
anticipated or probable impact velocities, the composition of the
outer helmet shell and the site and vector of probable impacts.
Arriving at the precise foam composition and thickness for the
impact energy absorbing liner involves matching the stiffness and
strength of the outer shell with the stiffness of the foam taking
into account the most critical impact velocities and vectors.
[0053] It is preferred to utilize the plaster fixture made from the
hardened headform as the "male" mold member 102 because this
fixture more accurately conforms to the shape and size of the
wearer's head 20 because it is cast in the same cavity once
occupied by the head. Using the headform 60 directly as the "male"
member 102 of the liner mold is faster (omits a step) than making
and using a plaster fixture, but is less precise and can result in
greater irregularity in the finished foam liner. But even if this
technique is used it may be necessary in some cases to stretch an
elastic material over the headform as described to allow for more
clearance for the foam spacers for air circulation in the
helmet.
[0054] In a preferred configuration the "female" mold member 103
splits into four sections as shown in FIG. 9 that slide out
allowing precise measurement of the molding space between the
"male" member 102 and the inner surface 105 of "female" member 103.
It will be understood that proper thickness and shape of this
molding space 108 is important, because there is a minimum foam
thickness for the energy absorbing liner that is necessary for
effective impact absorption. It is critical that the mold not be
cocked to either side or front to back during molding. On the
"male" member 102, markings are made for the eyebrows, the position
of the nose, for the position of the occipital ridge and for the
fore and aft horizon of the wearer. Most preferably, these markings
are made on the hardened headform 60 prior to removal from the
wearer's head to precisely locate these features for the particular
wearer. Alternatively, if a plaster fixture is made from the
headform, these markings are transferred to the fixture as it is
demolded from the headform. These markings will describe where the
head will be positioned in the helmet, and help to align the "male"
member to define the molding space.
[0055] It is important to pre-measure the volume to be foamed to
fill the molding space 108. Most preferably, this is achieved by
first measuring the volume of the female cavity 110, and then
subtracting that portion of the "male" member 102 that is inserted
into the cavity 110, whose volume can be determined by water
displacement. Once the precise volume of the molding space 108 for
the energy absorbing liner is known, the correct amount of the
foaming compound can be mixed to achieve the proper density of the
finished foam liner that will yield the proper energy-absorbing
characteristics.
[0056] As shown in FIG. 10, once the "male" and "female" mold
members 102 and 103 are in position defining the molding space 108
therebetween, a lid or collar 109 is placed at the opening of the
female cavity 110 around the perimeter of the "male" member 102 to
seal the molding space. The pre-measured foaming compound is then
provided or injected into the molding space, e.g. through the
collar 109. As the compound foams and expands, it fills the molding
space and rises to meet the collar, and the collar is held into
place rigidly until the foaming pressure has subsided. Once foaming
is complete, the collar is removed and the mold disassembled to
retrieve the finished impact energy absorbing foam liner having an
inner surface substantially conforming to the shape and contour of
the particular wearer's head. It is noted that according to the
invention, the finished impact energy absorbing foam liner is made
as one piece, and not from multiple pieces that are subsequently
joined via welding or other means. It is a one-piece liner whose
inner surface is substantially uniformly and continuously snugly
fitted to the wearer's head when the wearer is wearing the helmet,
thereby eliminated localized pressure points between the liner
surface and the wearer's head.
[0057] This liner is then fitted into an outer helmet shell and is
upholstered with fabric and leather as may be desired to provide a
custom fitted helmet for the wearer. A thin layer of soft open cell
foam spacer or spacers (conforming to the clearance thickness
described above) is typically placed between the upholstery and the
impact absorbing foam to provide a space for air circulation, and
holes are drilled in the foam to facilitate ventilation.
Alternatively, if the helmet shell is used as the "female" mold
member 103, it will be understood the liner formed therein is not
removed.
[0058] The present invention can be used to make an impact energy
absorbing liner having an inner surface substantially conforming to
the shape and contour of a particular wearer's head for a variety
of different helmets used in different applications. In a preferred
embodiment, the helmet for which the liner is made as described
herein is a motorcycle helmet. Alternatively, the helmet can be a
bicycle helmet, football helmet, hockey helmet, skiing helmet,
skydiving helmet, equestrian helmet, or other sports helmet, a
helmet for medical intervention for persons prone to seizures or
unconsciousness (narcolepsy), industrial protection helmet (e.g.
for manufacturing and construction workers), aircraft helmet
including military airplane and helicopter pilot helmets, etc.
[0059] The invention includes a kit comprising all of the materials
needed to make a hardened headform as described herein using the
beanie cap 10. Preferably, the kit includes the resin-impregnated
beanie cap 10, a protective barrier 30 (preferably latex or
silicone), protective gloves, waterproof apron and cape to shield
the wearer's body, serrated scissors for cutting the hardened
headform, a scissor guide (preferably plastic tube or plastic
strip), scissor cut resealing means (preferably super glue or
stapler), adhesive tape, a level, a ruler, printed casting
instructions and optionally an instructional video.
[0060] Although the hereinabove described embodiments of the
invention constitute the preferred embodiments, it will be
understood that modifications can be made thereto without departing
from the spirit and cope of the invention as set forth in the
appended claims.
* * * * *