Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD OF TREATING A SURFACE OF A UTENSIL
Field:
The present invention relates to utensils and the like. More particularly, the
present
invention relates to a method of treating a surface of a utensil as well as to
a utensil
having been treated by the method.
Background:
Known in the art are cooking vessels or baking vessels which have a non-stick
coating to prevent food from sticking to the vessel while the food is heated.
In order to improve the non-stick performance, manufacturers have developed a
wrinkle non-stick coating material. However this process presents numerous
drawbacks.
Hence, in light of the aforementioned, there is a need for an improved system
which,
by virtue of its design and components, would be able to overcome some of the
above-discussed prior art concerns.
Summary of the invention:
The object of the present invention is to provide a device which, by virtue of
its design
and components, satisfies some of the above-mentioned needs and is thus an
improvement over other related methods known in the prior art.
According to an aspect, the above mentioned object is achieved by method of
treating
a surface of a cooking utensil, the method comprising:
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a) providing a substrate to form a component of the cooking utensil, the
substrate
having a surface area to be treated; and
b) shot peening the substrate substantially evenly across the surface area
with
particles, for dimpling the substrate with depressions across the surface
area, to
reduce adhesion of matter on the treated surface area of the cooking utensil;
wherein the depressions formed at step (b) have an average depth ranging
between
about 0.1 mm and about 0.5 mm, and said depressions are substantially crater-
shaped.
In particular embodiments, the shot peening may comprise impacting the
particles
against the surface area with a density included between about 100
particles/cm3 to
about 350 particles/cm3. Moreover, each particle may impact the surface area
of the
substrate at a velocity ranging between about 10 m/sec. and about 30 m/sec.
Moreover,
each particle may impact the surface area of the substrate at an impact load
ranging
between about 0.65 PSI and about 2.5 PSI.
In particular embodiments, the depressions formed at step (b) have an average
depth
ranging between about 0.1 mm and about 0.5 mm. Each depression may have a
diameter ranging between about 1 mm and about 3 mm.
In particular embodiments, the particles of step (b) comprise a plurality of
balls, which
may be steel balls. Each ball may have a diameter ranging between about 1 mm
and
about 4 mm.
In particular embodiments, the method may comprise prior to step (b), cleaning
the
substrate to remove oxidation from a surface of the substrate. The method may
further
comprise after step (b):
sand blasting the surface area of the substrate; and
coating the surface area with a non-stick coating.
In particular embodiments, the substrate of step (a) is configured to form a
vessel of a
cooking utensil and the surface area to be treated includes at least a cooking
surface of
the cooking utensil. The surface area impacted by the shot peening may
comprise
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substantially a first surface of the substrate corresponding substantially to
an inner side of
the cooking utensil. Moreover, the impacted surface area may further include
at least a
portion of a second surface of the substrate, opposite to the first surface,
corresponding
to an outer side of the cooking utensil.
In particular embodiments, the substrate of step (a) is configured to form a
blade of a
cutting utensil and the surface area to be treated includes at least a contact
surface of the
cutting utensil.
In particular embodiments, the substrate may comprise cast iron, aluminum,
aluminum
alloy, stainless steel-aluminum, stainless steel, copper, other suitable
composite
materials, and/or the like.
According to another aspect, there is provided a utensil for handling food,
the utensil
comprising a treated surface having depressions distributed substantially
evenly across
said treated surface, the depressions having been formed through a shot
peening
process, wherein the depressions have an average depth ranging between about
0.1 mm
and about 0.5 mm, and said depressions are substantially crater-shaped, and
wherein
the utensil is a cooking utensil and the treated surface includes at least a
cooking surface
of the cooking utensil.
In particular embodiments, the treated surface comprises at least a contact
surface for
engaging with the food.
In particular embodiments, the utensil may be a cooking utensil and the
treated surface
may include at least a cooking surface of the cooking utensil. The cooking
utensil may
comprise a vessel. The treated surface may include at least an inner surface
of the
vessel. The treated surface may further include at least a portion of an outer
surface of
the vessel.
The cooking utensil may be a cooking pan or pot, a baking dish and/or the
like.
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In particular embodiments, the utensil may be a cutting utensil and the
treated surface
may include at least a cutting edge of a blade of the cutting utensil.
According to yet another aspect, there is provided a method of treating a
surface of a
utensil, the method comprising:
a) providing a substrate to form a component of the utensil, the substrate
having
a surface area to be treated; and
b) shot peening the substrate substantially evenly across the surface area
with
particles, to form depressions in the substrate across the surface area, for
reducing adhesion of matter on the treated surface area of the utensil.
According to yet another aspect, there is provided a blade for a cutting
equipment
comprising a contact surface for engaging matter to be cut, the contact
surface
comprising depressions distributed substantially evenly across the contact
surface,
said depressions being formed through a shot peening process.
According to yet another aspect, there is provided a cooking utensil
comprising a
cooking surface, the cooking surface having depressions distributed
substantially
evenly across the contact surface, said depressions being formed through a
shot
peening process.
Advantageously, the treated surface is enhanced with a physical anti-adherent
effect
and surface passivation effect resulting from a strong impact of the
particles, which
increases the density and strength of the substrate, increasing the rigidity
and
durability of the resulting utensil, as well as to increase durability of the
anti-adherent
effect.
Still advantageously, during cooking, liquids are stored in the pit of the
depressions
forming a film of fluid which cushions the food being cooked. This physical
non-stick
approach can effectively improve cooking performance by about three times in
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comparison with a cooking utensil made from a same material but without the
passivation treatment. The dimpled surface further reduces loss of nutrients
from the
food during the cooking process, as well as to reduce friction between the
food and
the cooking utensil.
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Other objects, advantages and features of the present invention will become
more
apparent upon reading of the following non-restrictive description of
preferred
embodiments thereof, given for the purpose of exemplification only, with
reference to
the accompanying drawings.
Brief description of the drawings:
FIG. 1 is a block diagram showing steps of a method, in accordance with an
embodiment.
FIG. 2 is a side plan view of a blank being treated by the method shown in
FIG. 1, the
blank being shown with a partial cut-away showing a cross-section of the
blank, the
blank being further shown with shot peening equipment, in accordance with an
embodiment.
FIG. 3 is another side plan view of the blank shown in FIG. 2, portions of the
blank
being shown in an enlarged view.
FIG. 4 shows vessel portions of cooking utensils having been treated in
accordance
with steps of the method shown in FIG. 1.
FIG. 5 shows cooking utensils having been manufactured in accordance with the
method shown in FIG. 1, the cooking utensils being shown with corresponding
covers.
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Detailed description:
In the following description, the same numerical references refer to similar
elements.
The embodiments, geometrical configurations, materials mentioned and/or
dimensions shown in the figures or described in the present description are
preferred
embodiments only, given for exemplification purposes only.
Broadly described, the embodiment described below concerns subjecting a
cookware
blank with steel balls to impact the surface densely and uniformly at high
speed and
kinetic energy to produce a homogeneous passivation layer having depressions
substantially shaped like meteorite craters. In addition, a non-stick coating
is applied
in order to achieve the dual effects of both physical and coating non-stick
properties.
More particularly, with reference to FIG. 1 to 5, there is provided a method
100 of
manufacturing a cooking utensil 200.
A substrate 202 (also referred to herein as "substrate blank" or "blank") is
shaped to
provide the vessel 204 (or "vessel portion") for the cooking utensil 200. The
vessel
typically has a diameter ranging from 12cm to 60cm, with a height of 25cm or
less.
A step 102 is directed to cleaning the shaped substrate blank 202 to remove
the oil
and aluminum alloy metal surface oxidation layer in order to achieve a clean
metal
molecule surface.
The cleaned and dry blank 202 is then subjected to a shot peening process 104
(also
referred to herein as "passivation"). More particularly, the shot peening
process
involves impacting the blank 202 with stainless and high strength alloy steel
balls 206
with a density of 200 particles/cm3 with a final velocity of 21m/sec,
providing an
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impact load of 0.92 N or 1.3 PSI. The balls 206 have a diameter of 2 mm. The
shot
peening process 104 provides the blank 202 with depressions 208 having a
substantially semi-spherical shape. The depressions 208 are distributed
substantially
homogeneously and substantially densely across the treated surface of the
blank
forming a concavely and convexed grooved (or "dimpled") surface 210.
The shot peening process is made by a high pressure jetting equipment line 216
having a double-front and double-back decompression chamber, where the steel
balls
206 move densely and uniformly at 3600, and additionally high pressure air
flow
cause the balls 206 to impact the treated surface evenly.
The depressions 208 on the dimpled surface 210 have an average depth of 0.2 to
0.3 mm and an average diameter ranging between 1 to 1.5 mm. The blank 202 is
subjected to the shot peening process on the inner side 212, and on an
exterior side
of the blank 214, for easier cleaning.
It is to be understood in accordance with alternate embodiments that the shot
peening
process may be applied to only one side of the blank 202 for example, and even
to a
portion of either side 212, 214 of the blank 202.
It is to be understood that depending on particular embodiments, the steel
ball
material may be a high-alloy steel ball (of type YG6, YG6X, YG8, YG8X, YN6,
YN9,
or the like), a stainless steel ball (of type 440C, 304, 316L, 420, 430, or
the like), or a
carbon low alloy steel ball (of type A3, 0195, Q235, AlS1010, AlS11015, or the
like).
In a subsequent step 106, the internal surface 210 is sand blasted using 40#
to 65#
high quality corundum to produce a microcosmic level rough surface of 2 to 4pm
in
depth, on the dimpled surface 210. This roughened surface ensures a better
adhesion of the non-stick coating, as will be explained further below.
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A post-cleaning step 108 cleans the metal wound without any incrustation
scale, and
includes cleaning agent spraying, hot water spraying, first cold water
spraying,
second cold water spraying, third cold water spraying, a first negative ion
water
spraying, a second negative ion water spraying, drying at a temperature of 85
C and
quenching with cool air.
At 110, 112, a non-stick coating is then sprayed and sintered on the internal
and
external surfaces 212, 214 of the blank 202.
At 114, a ring is machined on a bottom surface of the blank 202.
At 116, one or more handle 218 is then assembled onto the blank 202, to form
the
cooking utensil 200. It is to be understood that in alternative embodiments,
the handle
may be made integrally with the vessel portion of the cooking utensil.
Advantageously, the combined effects of both physical and non-stick coating
significantly improves the durability of the anti-adherent performance.
Experiments
show that under the same conditions, the service life of a cooking utensil
made with
the above-described method is increased by 3 to 5 times or more in comparison
to a
cooking utensil without being subjected to the above-described shot peening
process.
The shot peening process increases the density and strength of the metal
surface of
the cooking utensil, thereby improving the wear-resistance of the surface by
twice or
more in comparison to cooking utensils which have not been subjected to the
above-
described shot peening process.
It is to be understood that the cooking utensil may be a cooking pot or pan as
illustrated in FIG. 4 and 5, or any suitable cooking, heating or baking dish,
as may be
easily understood by the person skilled in the art. It is to be understood
also that the
above-described surface treatment method may be easily applicable to other
kitchen
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utensils such as knife blades, or even other equipment where anti-adherent
properties are desirable.
Inspection, measurements and tests were conducted as follows.
For the inspection of surface smoothness and roughness, an electronic
roughness
tester was used in combination with electron microscopy. The measured depth
ranged from 0.2 to 0.3 mm; the rounded surface diameter measured ranged from 1
to
1.5 mm, and the roughness measured 2 to 4 pm.
The hardness of the treated surface was measured by an electronic hardness
measuring instrument. The resulting hardness measured was HB 32 to 34 (the
surface hardness of ordinary 3003 aluminum plate is HB 25 to 27).
To measure the thickness of the non-stick coating, an aluminum plate measuring
10 x
10 x 1.5mm was placed in a cookware. This assembly was subjected to the spray-
painting of the non-stick coating material. The aluminum plate was then
removed from
the cookware for measuring the thickness of the coating by using an electronic
film
thickness measuring instrument.
A cross-cut peel test was made on the internal and external surface coating,
using a
cross-cutting device, according to the Standard Hundred Grids Test (QB/T2421-
98).
A slat water resistance test was conducted according to the QB/T2421-98
standard.
A dishwasher performance test was conducted according to the EN-12875-1
standard.
An oven test was conducted according to the EN-12983 standard.
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An LGA vibration and plane wear test were conducted according to the QB/T2421-
98/QB-T242-DuPont standard/ST009- Varberg standard.
A fried egg test was conducted to determine the life span of the cookware. The
5 cookware is heated up to 175 C, and an egg is placed in the cookware for
cooking.
The egg is easily separated after being cooked solid. Eggs are thus cooked
repeatedly using the same cookware. The test results in a failure when the egg
does
not separate easily before 300 repetitions are reached. The experimental
results
show that an egg could be cooked and separated easily from the same cookware
10 having been treated with the above-described shot peening process, 390
times. In
contrast, a cookware which was not treated with the shot peening process only
achieves 130 repetitions.
Although the above-described embodiment is directed to the manufacturing of a
cooking utensil, it is to be understood that embodiments of the present
invention may
be applied to manufacture civil, commercial and small household electrical
kitchenware made from cast iron, aluminum, aluminum alloy, stainless steel-
aluminum, stainless steel, copper and other composite materials, by
stretching,
punching, casting, die casting.
The above-described embodiments are considered in all respect only as
illustrative
and not restrictive, and the present application is intended to cover any
adaptations or
variations thereof, as apparent to a person skilled in the art. Of course,
numerous
other modifications could be made to the above-described embodiments without
departing from the scope of the invention, as apparent to a person skilled in
the art.
