U.S. patent application number 11/255415 was filed with the patent office on 2006-05-18 for custom-fitted helmet and method of making the same.
Invention is credited to Dan T. III Moore, Kathleen M. Novak.
Application Number | 20060101559 11/255415 |
Document ID | / |
Family ID | 37963315 |
Filed Date | 2006-05-18 |
United States Patent
Application |
20060101559 |
Kind Code |
A1 |
Moore; Dan T. III ; et
al. |
May 18, 2006 |
Custom-fitted helmet and method of making the same
Abstract
A helmet liner that is custom-fitted to a wearer's head, and
methods of making the liner, are provided. To make the liner,
scanning equipment directly scans the person's head to generate
computer-readable data containing a surface map of the head. This
data then is used by suitable machining equipment to machine a
custom-fitted liner from a universal liner blank, whose resulting
convex surface will substantially conform to the shape and contour
of the person's head. The scanning equipment desirably is or
includes one or a plurality of lasers. A mobile platform including
both the scanning and the machining equipment also is provided.
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: |
37963315 |
Appl. No.: |
11/255415 |
Filed: |
October 20, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10933580 |
Sep 3, 2004 |
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11255415 |
Oct 20, 2005 |
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10727725 |
Dec 4, 2003 |
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10933580 |
Sep 3, 2004 |
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60432193 |
Dec 6, 2002 |
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60620906 |
Oct 21, 2004 |
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Current U.S.
Class: |
2/410 ;
2/411 |
Current CPC
Class: |
B29C 33/3835 20130101;
B29C 44/60 20130101; B29C 44/1204 20130101; A42C 2/007 20130101;
B29C 44/56 20130101; B29C 2033/3871 20130101; A42B 3/12 20130101;
B29L 2031/4821 20130101; B29C 33/3857 20130101 |
Class at
Publication: |
002/410 ;
002/411 |
International
Class: |
A42B 1/06 20060101
A42B001/06 |
Claims
1. A method of making an energy-absorbing liner that is
custom-fitted to a wearer's head comprising: a) directly scanning a
person's head and generating computer-readable data comprising a
surface map of the person's head; b) providing a pre-made
energy-absorbing liner blank having at least one surface; and c)
machining said at least one surface of said energy-absorbing liner
blank, based on said computer-readable data, to provide a convex
surface therein whose shape and contour substantially conform to
the shape and contour of the person's head.
2. A method according to claim 1, said impact energy-absorbing
liner blank comprising viscoelastic foam.
3. A method according to claim 1, said impact energy-absorbing
liner blank comprising expanded polystyrene.
4. A method according to claim 1, said impact energy-absorbing
liner blank comprising expanded polypropylene.
5. A method according to claim 1, further comprising providing an
elastic cap over said person's head prior to scanning the head.
6. A method according to claim 1, said energy-absorbing liner blank
being made by molding a foaming composition in a mold, and curing
said foaming composition to provide said energy-absorbing liner
blank, said liner blank thereby being a foam liner blank.
7. A method according to claim 6, said energy-absorbing foam liner
blank comprising viscoelastic foam.
8. A method according to claim 6, said energy-absorbing foam liner
blank comprising expanded polystyrene.
9. A method according to claim 6, said energy-absorbing foam liner
blank comprising expanded polypropylene.
10. A method according to claim 6, said foaming composition
comprising isocyanate and at least one polyol.
11. A method according to claim 1, said person's head being scanned
by one or a plurality of lasers to generate said computer-readable
data comprising a surface map of said person's head.
12. A method according to claim 11, wherein a first scanning laser
is oriented at an angle of 45.degree. to the person's spine from
above said person's head.
13. A method according to claim 12, wherein a second scanning laser
is oriented either at an angle of 90.degree. to the person's spine
or parallel to the person's spine.
14. A method according to claim 11, wherein a first scanning laser
is oriented at an angle of 90.degree. to the person's spine and a
second scanning laser is oriented parallel to the person's
spine.
15. A method according to claim 1, further comprising providing
said impact energy-absorbing liner in a motorcycle helmet.
16. A method according to claim 1, further comprising manipulating
said computer-readable data to increase an effective radius along
at least a portion of the surface map of said person's head in
order to provide a predetermined clearance to accommodate the
installation of comfort fitting foam into a helmet adjacent a
finished energy-absorbing liner made from said liner blank.
17. A method according to claim 1, said energy-absorbing liner
blank being machined using CNC machinery, based on said
computer-readable data, to provide a finished energy-absorbing
liner having said convex surface therein whose shape and contour
substantially conform to the shape and contour of said person's
head.
18. A method according to claim 17, said CNC machinery comprising a
CNC router.
19. A method according to claim 1, said computer-readable data
being generated by scanning said person's head using a scanner or a
coordinate measuring machine capable of directly scanning the head
to measure the surface dimensions and contour thereof.
20. A helmet that is custom-fitted to a particular wearer's head,
the helmet comprising an impact energy-absorbing liner made
according to the method of claim 1.
21. A helmet that is custom-fitted to a particular wearer's head,
the helmet comprising an impact energy-absorbing liner made
according to the method of claim 11.
22. A helmet according to claim 21, said energy-absorbing liner
comprising viscoelastic foam.
23. A helmet according to claim 21, said energy-absorbing liner
comprising semi-rigid viscoelastic foam.
24. A helmet according to claim 21, said energy-absorbing liner
comprising expanded polystyrene.
25. A helmet according to claim 23, said foam exhibiting
substantially 100% crush recovery following an impact.
26. An apparatus for producing a custom-fitted energy-absorbing
liner, comprising means for directly scanning a person's head to
generate computer-readable data comprising a surface map of said
person's head, and means to machine an impact energy-absorbing
liner blank to provide a convex surface therein whose shape and
contour substantially conform to the shape and contour of said
person's head, both said scanning means and said machining means
being provided on a mobile platform.
27. A combination according to claim 26, said mobile platform being
a trailer or a truck.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/620,906 filed Oct. 21, 2004, and
also is a continuation-in-part of U.S. patent application Ser. No.
10/933,580 filed Sep. 3, 2004, which is a continuation-in-part of
U.S. patent application Ser. No. 10/727,725 filed Dec. 4, 2003,
which claims the benefit of U.S. Provisional Patent Application
Ser. No. 60/432,193 filed on Dec. 6, 2002, all of which are
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
at 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 harmful 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 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.
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.
[0009] 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.
[0010] 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 is snugly and uniformly
fitted to the shape and contour of the head.
SUMMARY OF THE INVENTION
[0011] A method of making an energy-absorbing liner that is
custom-fitted to a wearer's head is provided. The method includes
the following steps: a) directly scanning a person's head and
generating computer-readable data including a surface map of the
person's head; b) providing a pre-made energy-absorbing liner blank
having at least one surface; and c) machining the at least one
surface of the energy-absorbing liner blank, based on the
computer-readable data, to provide a convex surface therein whose
shape and contour substantially conform to the shape and contour of
the person's head.
[0012] An apparatus for producing a custom-fitted energy-absorbing
liner is provided. The apparatus includes means for directly
scanning a person's head to generate computer-readable data
comprising a surface map of said person's head, and means to
machine an impact energy-absorbing liner blank to provide a convex
surface therein whose shape and contour substantially conform to
the shape and contour of said person's head. Both the means for
scanning the head and the means for machining the liner blank are
provided on a mobile platform.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a side view of a beanie cap for preparing a
headform that can be used to make 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.
[0014] 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.
[0015] 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.
[0016] 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 making an
energy-absorbing liner for a helmet having an inner surface
substantially conforming to the shape and contour of the person's
head.
[0017] 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.
[0018] 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.
[0019] 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 making an energy-absorbing liner for
a helmet having an inner surface substantially conforming to the
shape and contour of the person's head.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] FIG. 11 is a schematic process diagram for making a
custom-fitted helmet using CNC machinery according to a preferred
embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
[0024] 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.
[0025] One 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 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.
[0026] 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. (It is noted the headform may
undergo additional hardening or curing after it is removed from the
wearer's head). The 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.
Alternatively, in a further preferred embodiment described more
fully below, the hardened headform can be scanned by suitable
scanning equipment to generate a computer-readable data file of a
surface map of the headform (i.e. digitizing the headform). This
data file is then used to direct CNC machinery, or other computer
controlled milling device or tool, to machine a pre-made
energy-absorbing liner "blank" so as to provide an inner surface
thereof having a complementary contour to the wearer's head. In a
further embodiment also described below, the scanning equipment can
scan the wearer's head directly to generate the computer-readable
data in the manufacture of a custom-fitted liner.
[0027] 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.
[0028] 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 orientation in its uncured state, the beanie cap 10 will
tend to return to its initial shape at rest once the external
stretching force has been removed. 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.
[0029] 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 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, 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.
[0030] 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 made using the headform made by
hardening 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 the head preferably are marked on
the beanie cap 10.
[0031] 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 or cut away so
as not to cover the wearer's eyes and to facilitate removal of the
hardened headform once it is complete.
[0032] 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.
[0033] After the headform 60 has hardened, it is carefully removed
from the head and used in subsequent molding or scanning operations
described below. To remove the hardened headform it is sometimes
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.
[0034] 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.
[0035] 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.
[0036] FIGS. 4-6 illustrate a heat-softenable plastic sheet 40
according to the invention as well as a 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
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.
[0037] 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.
[0038] FIG. 7 illustrates 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 compliant 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.
[0039] 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 fully 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.
[0040] 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.
[0041] 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 made
energy-absorbing liner (molded from the headform, whose mold is
made using the headform, or made using CNC machinery 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.
[0042] 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 comfort foam spacer or
spacer(s) to provide for wearer comfort and allow for air
circulation, as well as to accommodate 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 comfort foam spacers and the
upholstery material. 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. In a further
alternative, when the energy-absorbing liner is made using CNC
machinery based on a digitized file of the headform surface
contour, the digital headform map is manipulated using appropriate
software to provide the desired clearance (described more fully
below). In this case, it is not required to use a hood (FIG. 8)
when making the headform.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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 the 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.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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 may involve 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.
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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 10 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.
[0056] 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
comfort 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.
[0057] An alternative, further preferred method for making the
custom-fitted helmet using the hardened headform also is provided.
This method involves scanning the headform or a fixture made from
the headform to generate a computer-readable data file containing a
digitized map of the shape of the wearer's head, and using the
digitized map to control CNC machinery to provide the corresponding
surface contour on the inner surface of a pre-made energy-absorbing
liner "blank." This method now will be described in detail.
[0058] In conjunction with the following description, reference is
made to FIG. 11 which schematically depicts a method for making a
custom-fitted helmet using CNC machinery. In this method, the
hardened headform 60 is produced as described above via one of the
above-described methods. Alternatively, the headform 60 can be
produced via any suitable method that is effective to produce a
headform that conforms to the contour of a person's head.
Preferably, the headform 60 is marked up with suitable contour
lines and other suitable notation to indicate the relative
positions on the headform corresponding to particular points on the
wearer's head. For example, the headform may be marked with a line
parallel to the ground to indicate up and down orientation, a point
to indicate the location of the occipital ridge on the skull, lines
indicating the positions of the eyebrows, and a point to indicate
the center of the head (the nose).
[0059] Then the headform is delivered to a scanner or other
suitable machine (such as a coordinate measuring machine) capable
of scanning the headform using known or conventional methods, most
preferably using lasers, to measure the surface dimensions and
contour of the headform. The above-noted contour lines and other
notation marked on the headform provide suitable reference points
for the scanning machine to generate a corresponding electronic
solid form model of the headform as known in the art (i.e. to
digitize the scanned headform). Suitable scanners are available,
e.g., from Cyberware, which produces a variety of laser-based
scanners capable to generate three-dimensional solid form models in
computer-readable form. The scanner is equipped with or coupled to
a processor that is capable of generating electronic
computer-readable data comprising a digitized surface map of the
headform, corresponding to the wearer's head. This
computer-readable data is then fed into or used by a computer
controller that is coupled to suitable CNC machinery to control the
operation of the machinery. The CNC machinery can be, e.g., a CNC
router or any other known or conventional type of milling machine
or tool that is amenable to CNC control so as to produce, via
routing, milling or other machining operation of the machine or
tool, an inner surface of a "blank" liner that conforms to the
digitized surface map of the headform in the computer-readable data
file. Such suitable CNC machinery, including CNC routers, are well
known and conventional in the art and their operation will not be
further described here.
[0060] To produce a custom fitted energy-absorbing liner using the
suitable CNC machinery described above, an energy-absorbing liner
blank is supplied and retained in a suitable fixture so that the
CNC machinery can operate on the blank based on the information in
the computer-readable data file. According to the invention, an
energy-absorbing liner blank is made, e.g. via molding or other
suitable means, whose outer convex surface conforms to the helmet
shell in which the liner will be mounted, and whose inner concave
surface is generally dome- or hemispherically-shaped. The inner
concave surface is provided having a relatively small diameter
compared to a typical human head. In this manner, the CNC machinery
or router can produce a desired inner surface contour based on the
digitized headform data map by milling, grinding away or otherwise
machining liner material from the inner surface of the blank until
the appropriate headform dimensions are achieved. Once the desired
final inner concave surface has been achieved, the surface is or
can be coated with a suitable coating to make it impermeable to
moisture.
[0061] Alternatively, the energy-absorbing liner blank can be
provided as a solid hemispherical form having a convex
hemispherical surface and a flat, circular surface with
substantially no initial concavity. The operation of the CNC
machinery or router to produce the desired inner concave surface of
appropriate dimensions based on the digitized headform map proceeds
substantially as described in the preceding paragraph, except now
the CNC machinery has to grind away a greater volume of material.
This embodiment has the advantage that it can be used to
accommodate a larger range of head sizes because there is no
initial concave inner surface and hence no head that will be too
small to use the blank. However, this embodiment also results in a
substantial waste of liner material due to the additional wasted
material that must be removed to produce the desired inner concave
surface for a particular wearer.
[0062] Alternatively, and most preferably, blanks can be provided
in a number of predetermined stock sizes, such as small, medium,
large, extra-large, etc., where the size notation refers to the
initial dimensions of the inner concave surface in the blank. For
example, a small blank may have an inner concave surface whose
hemispherical circumference is 15 inches. This size may be
suitable, e.g., for persons whose mean head circumference is in the
range of 16-17 inches. A medium blank may have an inner concave
surface whose hemispherical circumference is 16 inches, and may be
suitable, e.g., for persons having a mean head circumference in the
range of 17-18 inches, and so on. (The numerical values used in
this paragraph are for illustrative purposes only).
[0063] The present method has the further advantage that no hood 65
(see FIG. 8) need be employed to provide adequate clearance to
accommodate comfort foam padding or upholstery because suitable
clearance can be achieved using appropriate computer software to
modify the digitized headform map once it is in computer-readable
form. Specifically, the computer controller can be programmed with
suitable software so as to increase the effective radius along the
entire surface map to accommodate an extra 1/4 inch or 1/8 inch
gap, or any other suitable dimension, as may be desirable or
preferable to accommodate the installation of comfort fitting foam
into the helmet adjacent the finished liner. Furthermore, the
software can be programmed so that the increased radius is present
only along certain portions of the head surface where comfort
fitting foam will be employed, or even so that the clearance radius
is different from one location to the next if appropriate. This is
a substantial benefit as the hood 65, when used, can introduce a
substantial variable into the production of the headform 60 that
may affect its accuracy as a model of the shape and contour of the
wearer's head.
[0064] It is contemplated that a kit for making the hardened
headforms 60 can be supplied to retail locations where persons may
wish to purchase a custom-fitted helmet, and that the other more
expensive equipment, scanner, computer equipment, CNC control
equipment, CNC machinery, etc., will be maintained at a fixed
location to which hardened headforms can be sent by the retail
locations once they have been made. Generally, a person seeking a
custom-fitted helmet would patronize one of the retail locations,
and a technician employed by the retail store would be trained to
prepare the headform from the person's head using the kit (one
exemplary such kit is described below). Having completed the
headform, the technician would permit it to harden or cure, and
then send it back to the fixed location where the other equipment
is located, for example in a specialized shipping container which
may be supplied with the kit. Then, the headform would be used at
the fixed location to produce the corresponding custom fitted
energy-absorbing liner 90. This liner either could be shipped back
to the retail location, where the person then could select from a
variety of helmet shells into which the liner can be installed, or
otherwise the liner can be installed into a desirable helmet shell
according to the person's specifications based on, e.g., a catalog
selection.
[0065] The present invention, including methods and means for
producing a precisely fit custom-fit helmet has a number of
significant advantages. The custom fit feature allows the retailer
to reduce his inventory of helmets and yet achieve a perfect fit
for his customers. If a retailer has five different styles with
five sizes in each and five different colors, and if he keeps two
of each in stock, that is an inventory of 250 helmets. With a
custom-fit helmet according to the invention the retailer could
display the same five styles, and have a color chip for perhaps as
many as ten or more colors. Because there is precise clearance
between the inner surface of the energy-absorbing liner and the
wearer's head, it is possible to provide a cooling and refreshing
flow of air between the helmet and the head. Conventional helmets
require thick padding that inhibits the flow of air. There is less
padding in a custom-fit helmet according to the present invention
for a given exterior helmet shell dimension, and more
energy-absorbing foam (the energy-absorbing liner) than is possible
with a conventional helmet by virtue of the fact that there is less
comfort foam. This thicker energy-absorbing liner leads to a safer
helmet. Because the helmet fits snugly, it has less tendency to
roll back at high speeds because it is more stable on the head.
Also, even with a perfect fit conventional helmet, due to the
standardization of the helmet liner typically there is one spot on
the head that rubs harder for a particular wearer, where contact
between the liner and the head is more intimate, than the rest of
the head. Over prolonged use, for example during a long motorcycle
ride, this is irritating to the wearer. With a custom-fit helmet
according to the invention, there are no such over-tight spots
because the liner is fit precisely to the contour of the particular
wearer's head.
[0066] 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, kayaking
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.
[0067] A kit also is included, which comprises 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.
[0068] Thus far, in the foregoing methods a custom-fit helmets is
made by first producing a model of a person's head, a headform,
(e.g. from a resin-impregnated beanie cap made from elastic
material), and then using that headform to mold (or to prepare a
mold for) a foam energy-absorbing liner. The resulting liner is
custom-fit to the contour of the person's head from which the
headform was prepared.
[0069] The approaches described above will work well to produce
custom-fit helmets in response to much of the demand for such
helmets, probably more than 90% of the anticipated custom-fit
helmet market. For one thing, the use of a hardened headform as
described above will permit point-of-sale fitting for a helmet, and
then sending the headform back to a fixed location where the
helmets are manufactured. Once a particular custom-fit helmet is
manufactured based on a particular headform, the finished helmet is
shipped back to the point-of-sale where it can be picked up by the
customer. This method will prove very convenient for most
custom-fit helmet customers, who can pick up their helmets at the
point-of-sale. It also will permit many point-of-sale shops, who
cannot afford the expensive equipment and do not have the expertise
to manufacture a custom-fit liner from a liner blank, nonetheless
to participate in the custom-fit-helmet market. It is contemplated
that for most such shops, the frequency of the demand for
custom-fit helmets will not be sufficient to justify the investment
in machinery and training necessary to make custom-fit helmet
liners on site.
[0070] However, by using a headform to approximate the anticipated
wearer's head, there is introduced into the custom fitting process
a potentially significant source of error. Namely, the headform may
be susceptible to damage, e.g. while in transit from a
point-of-sale where it was made to a fixed location where it is to
be used to make a custom-fit liner. The use of a headform also may
introduce additional unforeseeable variables into the custom
fitting process. Consequently, in circumstances where it is
practical to have the anticipated wearer and scanning or digitizing
equipment present at the same location, a further preferred
embodiment involves scanning the person's head directly using the
scanning and digitizing equipment, instead of going through a
headform as an intermediate. In this method, the scanning equipment
obtains information and measurements directly of the person's head
to generate the computer-readable data for (digitize) a head
contour map as described above. The process proceeds similarly as
illustrated in FIG. 11, except that the person's head is
substituted for the headform 60 illustrated schematically in that
figure. It is contemplated this embodiment will be desirable
particularly where large scale helmet fitting opportunities exist,
for example, 100 people are to be fitted in several days.
Specifically, a scanner or other suitable machine (such as a
coordinate measuring machine) capable of directly scanning a
person's head measures the surface dimensions and contour of the
head. If appropriate, contour lines or other notation can be marked
on the person's head prior to scanning, which act as reference
points for the scanning equipment. Most preferably, the scanning
equipment uses lasers to scan the head, and includes or is coupled
to a processor that is capable of generating electronic
computer-readable data comprising a digitized surface map or solid
surface model of the scanned head. This computer-readable data is
then fed into or used by a computer controller that is coupled to
suitable CNC machinery to control the operation of the machinery,
which then produces a custom-fit liner from a liner blank (such as
by milling) as already described. As noted, the scanning equipment
preferably uses lasers to produce a solid form model from which the
computer-readable data is generated. Less preferably, other surface
contour mapping equipment, which can be or is coupled to a
processor for generating the computer-readable data, can be used,
such as machinery using one or a plurality of styluses to measure
the head's surface contour mechanically.
[0071] By directly scanning and measuring head shapes and skipping
the step of the preparing or using a separate headform, substantial
time and cost savings are possible when the wearer and the scanning
equipment can be located in the same place. Also, a substantial
opportunity for the introduction of error is avoided. There are
points that should be kept in mind when scanning and digitizing the
head.
[0072] When laser scanning any predominantly round object, the
highest fidelity that is achieved is where the angle between the
surface and the laser is 90.degree.. Lesser angles may result in
lost fidelity. As an example, if the scanning laser is directed at
an angle that is 90.degree. to the spine of the person being
measured, the best fidelity would be for scanning the circumference
of the head, e.g. at the level of the nose, and the worst would be
for scanning the top of the head. This is because the laser would
be essentially parallel or tangent to the uppermost surface portion
of the head, and so would not produce a very accurate contour map
of that portion. One way to correct this problem is to use a single
laser that is oriented at an angle of 45.degree. to the spine, so
that both the circumferential portion and the uppermost surface or
crown portion (which is of substantial concerned when fitting an
energy-absorbing helmet liner) of the head can be scanned and
contour maps generated with a reasonable degree of accuracy.
Assuming the laser source is angled at 45.degree. to the spine from
a location generally above the head, this will leave the base
portion of the head less well defined. However, the base portion is
of the least concern when fitting an energy-absorbing liner.
[0073] Alternatively, a plurality of scanning lasers can be used to
collect surface contour data, for example one at an angle of
90.degree. to the spine for providing the most accurate contour
data for the perimeter of the head, and a second laser at an angle
parallel to the spine whose source is located generally above the
head to provide the most accurate contour data for the crown
portion of the head. Alternatively, in addition to or instead of
one of these two lasers, a laser angled at 45.degree. to the spine
also can be used. When all three of these lasers are used, very
accurate surface contour maps of the head can be generated. When
multiple lasers are used, a processor collects all of the data from
each of the lasers and executes an algorithm to `fit` all the data
together to construct a solid form model of the head surface, and
generate computer-readable data that can be subsequently used,
e.g., by CNC machinery to manufacture a custom-fit liner from a
liner blank.
[0074] As described above, the computer readable data can be
manipulated to add a specified thickness to the digitized head
form, to allow room for relatively soft comfort or `fit` foam to be
placed in the head cavity of a resulting custom-fitted liner so the
helmet does not fit too tightly and so that there is room for air
to circulate between the scalp and the liner. This specified
thickness is generally between 1/8'' and 1/4'' as mentioned
above.
[0075] It is also desirable that when a head is scanned, an elastic
cap or beanie that fits relatively tightly against the wearer's
head is worn to provide a more uniform, substantially smoothly
contoured target for the laser, and to compress the person's hair
uniformly as it would be compressed in a helmet. Once the
computer-readable data has been generated, the data can be used
similarly as already described to produce or manufacture a
custom-fit helmet liner from a liner blank.
[0076] Also as noted, it is possible to directly scan the head
using more traditional coordinate measuring machines, such as those
employing a mechanical arm or stylus. These machines are slower at
scanning but less expensive than the laser scanning devices
currently available. Another advantage to laser scanning is that a
trained technician using a laser scanner can often provide a better
fit by noting head shape and changing the standardized offset
distance (to allow for the fit foam) depending upon the head shape.
For example, a head that is very flat on the top can get by with
tighter tolerances than a head that is more pointed. Thus a pointed
head may need 1/4'' offset where a flat head on top the offset
could be more like 1/8''.
[0077] It is contemplated that all the scanning, digitizing and
milling equipment can be provided or mounted in a mobile platform,
for example, in a truck or trailer, or other transportable mode,
such that the equipment can be transported conveniently to a place
where a large number of helmets are to be produced or have been
ordered. For example, a mobile platform such as a trailer
containing the equipment could be driven or transported to a
military base to fit military pilots for their helmets, or infantry
for their combat helmets, or to a sports arena to fit players'
helmets. Alternatively, the equipment could be transported to any
other location where a relatively large number (to offset the
equipment and method costs) of high quality, custom-fitted helmets
are to be produced such as trade shows, auto race tracks, or
virtually anywhere else.
[0078] 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.
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