FIELD OF INVENTION
[001] The present invention relates to a method of cladding for flame retardancy in
general, and method for cladding a light weight ballistic helmet and the ballistic helmet made by the method thereof.
BACKGROUND OF THE INVENTION
[002] Helmet is used as a protective gear worn on head portion of a user to protect it
from injuries. The helmet includes a securement system, such as a chin strap, a nape strap and the like, for removably securing the helmet to a head portion of a user. Helmets may be used for various purposes such as recreational activities, sports, construction, mining, police and military applications. The Police, military and other law enforcement agencies personnel wear the helmet to protect their head from hand held firearms and high velocity fragments.
[003] Generally, the ballistic helmet is composed of Aramid or para-Aramid fabrics.
The Aramid or p-Aramid fabrics offer good ballistic protection. However weight is a problem with the Aramid and p-Aramid fabrics. Police, military and other law enforcement agencies personnel are required to carry lot of equipments while on missions. Every extra ounce can hamper their mobility and reduce their combat performance. Accordingly, it becomes necessary to keep the overall weight of the equipments including the ballistic helmet as low as possible without compromising protection and performance.
[004] One of the main problems of developing helmet is to obtain weight reduction.
Prior art shows improvement in design and materials used have brought further weight reduction.
Indian patent application no. 2095/DEL/2007 discloses the method of making light weight helmet where light weight is achieved by using polyethylene fabric material.
[005] It is known from the prior art that polyethylene is easily susceptible to fire.
Physical and ballistic property of the polyethylene helmet can get affected adversely when they come in contact with fire. They have poor flame retardancy. Existing polyethylene helmet cannot survive the flame.
[006] It is also known from the art that paint acts as a protective surface which increases
the durability and lifecycle of said product apart from giving aesthetic appeal. Existing polyethylene helmet provide negative surface for paint adhesion.
[007] Accordingly, based on the foregoing problems, there exists a need of light weight
ballistic helmet with increased flame retardancy and paintablity.
[008] The present invention overcomes the present drawback and provides a solution
for increasing the flame retardancy and adhesion surface of the helmet. In general the invention contemplates a method of cladding for fire retardancy for use in protective articles such as helmet containing respective inner and outer layers of special synthetic fabrics and plurality of middle layers of polyethylene fabrics. Further, the polyethylene surface of light weight helmet of prior art was difficult to paint. The provision for outer layer made of a specific synthetic fabric provides a good surface for proper paint, thus increasing the flame retardancy capacity of the helmet.
SUMMARY OF THE INVENTION
[009] In view of the foregoing disadvantages inherent in the prior art, the general
purpose of the present invention is to provide a method of making a helmet configured to include
all the advantages of the prior art, and to overcome the drawbacks inherent therein.
[010] An object of the invention is to provide a light weight helmet with increased
flame retardancy.
[011] Another object of the invention is to provide a light weight helmet with increased
adhesion surface for paintability.
[012] Still another object is to narrate a method for making helmet in which the resin
chemistry which is coated over the special synthetic fabric layers used for outer cladding is appropriately chosen, so that it matches with the resin of the polyethylene layers of the helmet shell. This is done to achieve increased adhesion of special synthetic fabric layers to polyethylene fabric layers & also done to have the cladding molded in the same cycle as polyethylene layers.
[013] Yet another object is to provide a light weight flame retardant helmet without
impairing the ballistic property.
[014] Accordingly, the present invention provides a method of making helmet. The
method includes cutting a plurality of helmet pre-forms from a ballistic fabric material, sandwiching the plurality of layer of polyethylene fabric between the outermost and innermost layer of special synthetic fabric, positioning the plurality of helmet pre-forms in a mold cavity, the mold cavity configured to have a shape of a helmet shell, subjecting the plurality of helmet pre-forms in the mold cavity to a pressure in a range of about 180-200 kg/cm2 and heating the
plurality of helmet pre-forms in the mold cavity to a temperature in a range of about 100 to 130°C for a time period of about 5 minutes to 20 minutes.
BRIEF DESCRIPTION OF THE DRAWING
[015] FIG. 1 illustrates a perspective view of a helmet, according to an embodiment of
the present invention;
[016] FIG. 2 illustrates a top view of a helmet pre-form of the plurality of helmet pre-
forms, according to an embodiment of the present invention;
[017] FIG. 3 illustrates a perspective view of the plurality of helmet pre-forms to form a
shell of the helmet, according to another embodiment of the present invention;
[018] FIG. 4 illustrates the cross sectional view of helmet shell according to an
embodiment of the present invention. Shown is the arrangement of inner and outer layer of synthetic fiber for cladding.
[019] Like reference numerals refer to like parts throughout the description of several
views of the drawings.
DTAILED DESRIPTION OF THE INVENTION ACCOMPANIED BY DRAWING
[020] The exemplary embodiments described herein detail for illustrative purposes are
subject to many variations in structure and design. It should be emphasized however that the
present invention is not limited to a particular method of cladding light weight helmet as shown and described. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but these are intended to cover the application or implementation without departing from the spirit or scope of the claimed inventions.
[021] Referring to FIG.l to FIG. 4, a method of making a helmet 100 is illustrated.
More specifically, FIG.l illustrates a perspective view of the helmet 100; FIG. 2 illustrates a top view of a helmet pre-from of the plurality of helmet pre-forms, FIG.3 illustrates a perspective view of the plurality of helmet pre-forms positioned in a mold cavity and FIG 4 illustrates the cross sectional view of helmet shell
[022] The shell of helmet is composed of plurality of layers where middle layer of
plurality of polyethylene fabrics are sandwiched between outermost and innermost layers of special synthetic fabrics. The presence of Polyethylene layers for ballistic properties ensures that the weight of the helmet is on lower side. However the presence of special synthetic fabric ensures that the helmet acquires flame retardant properties. Thus the novel combination of Polyethylene for middle layer and special synthetic fabric for outermost and innermost layer provides a light weight flame retardant helmet.
[023] Polyethylene surface of light weight helmet of prior art was difficult to paint. The
provisions for outer layer made of special synthetic fabric provide a good surface for proper painting also.
[024] The preferred embodiments of the invention provide the structure that is fire
retardant, has increased adhesion properties, is penetration resistant, light weight, and is sufficiently stiff to serve as a platform for mounting accessories.
[025] The helmet is composed of a plurality of helmet pre-forms. The plurality of
helmet pre-forms is cut from materials with ballistic properties. In one embodiment of the present invention, the ballistic sheet material and accordingly the plurality of helmet pre-forms is composed of a polyethylene fabric material and special synthetic fabric material.
[026] More specifically the polyethylene fabric material used is ultra high molecular
weight polyethylene in fabric form. On the other hand the special synthetic fabric used is resin coated, wherein one of the surfaces of helmet pre-forms of special synthetic fabric is coated with suitable resin at room temperature. The coating is done with appropriately chosen resin to match the resin chemistry of polyethylene layers.
[027] Further, each of the plurality of helmet pre-form is positioned in a mold cavity
with the centers of the plurality of helmet pre-forms aligned. The mold cavity is configured to have a shape of a helmet shell. Further, each of the plurality of helmet pre-forms is positioned over the other in a way such that each subsequent helmet pre-form is rotated. In one embodiment of the present invention, the plurality of helmet pre-forms is positioned manually in the mold cavity.
[028] These helmet pre-forms are positioned in such a way that the resin coatings of
outer and innermost layer of special synthetic fabric faces the middle polyethylene layers and plurality of middle layer of Polyethylene pre-forms is sandwiched between the outermost and innermost layer of special synthetic fabric material pre-forms. The number of the plurality of helmet pre-forms is based on the degree of protection required. Further, each of the plurality of helmet pre-forms, such as the helmet pre-form, may be configured to have a variety of shapes.
[029] Furthermore, the plurality of helmets pre-forms positioned in the mold cavity is
subjected to a pressure in a range of about 180-200 kg/cm2. Concurrently, the plurality of helmet pre-forms in the mold cavity is heated to a temperature range of about 100 to 130°C for a time period of about 5 minutes to 20 minutes. In one of the embodiments of the present invention the plurality of helmet pre-forms positioned in the mold cavity is heated to a temperature of about 128°C and subjected to a pressure of about 180 kg/cm2 for about 10 minutes. The plurality of helmet performs may be subjected to the above mentioned pressures by means known in the art.
[030] In one embodiment of the present invention, the pressure may be applied by
means of a complimentary die. Further, the plurality of helmet pre-forms in the mold cavity may be heated to the above mentioned temperatures by various means known in the art. Accordingly, after subjecting to the above mentioned heat and pressure, the plurality of helmet pre-forms is allowed to cool. After subjecting to above mentioned procedure including positioning in the mold cavity heating, applying pressure and cooling the plurality of helmet pre-forms results into the helmet shell.
[031] Further, the helmet shell may undergo a surface preparation process before final
painting. Still further, a chin strap mechanism may be disposed on the helmet for releasably securing the helmet to a head portion of a user. In one of the embodiments, the present invention may include chin strap mechanism.
[032] Although the exemplary embodiments described herein describe the helmet,
particularly for ballistic protection helmets, the present invention is not intended to be exhaustive or to limit to a ballistic protection helmet. The principles of the present invention may be equally applied to helmets utilized in various fields such as recreational activities, sports, construction, mining and the like.
[033] Various embodiments of the present invention offer advantages namely, the
method of making a helmet and helmet made there-from, as described herein, is capable of being protecting the head portion of a user from injuries and is capable of decreasing the weight of the Ballistic protection helmet. Furthermore the method is capable of making a helmet which has increased retardancy for fire and increased surface adhesion property. Further the helmet produced by this method has better durability.

We claim:
1. A method of cladding of a light weight helmet for flame retardancy, comprising the steps
of:
a. cutting a plurality of helmet pre-forms from ballistic fabric sheet materials;
b. sandwiching the plurality of middle layer of helmet pre-forms;
c. positioning the plurality of helmet pre-forms in a mold cavity, wherein the mold cavity
configured to have a shape of a helmet shell;
d. subjecting the plurality of helmet pre-forms in the mold cavity to a pressure in a range of
about 180-200 kg/cm2;
e. heating the plurality of helmet pre-forms in the mold cavity to a temperature in a range of
about 100°C to 130°C for a time period of about 5 minutes to 20 minutes.
2. The method of cladding of a light weight helmet for flame retardancy as claimed in claim 1, wherein the plurality of helmet pre-forms is configured to have a flower shape.
3. The method of cladding of a light weight helmet for flame retardancy as claimed in claim 1, wherein the middle layer of helmet pre-forms is sandwiched between special outermost and innermost layers of helmet pre-forms.
4. The method of cladding of a light weight helmet for flame retardancy as claimed in claim 1 and 3, wherein the outer most and inner most layers of helmet pre-forms are composed of special synthetic ballistic fabric material.
5. The method of cladding of a light weight helmet for flame retardancy as claimed in claim 1, wherein the middle layer of helmet pre-forms is composed of plurality of polyethylene fabric material.
6. The method of cladding of a light weight helmet for flame retardancy as claimed in claim 1, wherein the plurality of helmet pre-forms positioned in the mold cavity is heated to a temperature in between 100°C to 120°C and subjected to a pressure of about 180kg/cm2 for about 10 minutes.
7. The light weight helmet for flame retardancy made of according to the method as claimed in claim 1.