FIELD OF THE INVENTION
The present invention relates to a process for application of polymer, ceramic or
metal coatings on a moving steel sheet substrate.
BACKGROUND OF THE INVENTION
A wide range of polymer, metal and ceramic materials have been processed by
three dimensional printing technologies. The printer (Object Geometries) prints a
number of different layers of acrylic-based photopolymer materials of 0.0006
inches thickness from heads containing 1,536 individual nozzles. Each
photopolymer layer is cured by ultraviolet light immediately as it is printed,
producing fully cured models without post-curing. Support structures are built in
a gel-like material, which is removed by hand and water jetting(1). Only two
different photopolymers can be printed at one time; however, by automatically
adjusting build styles, the machine can print up to 25 different effective materials
by varying the relative composition of the two photopolymers. The ProJet
printers print layers 0.0016 inches thick using heads with hundreds of nozzles,
half for part material and half for support material (2) Layers are then flashed
with ultraviolet light, which activates the photoinitiated polymerization.
Ceramic materials are also used for three-dimensional structures fabrication by
direct printing process. It is known that a mixture of zirconia power, solvent, and
other additives, is enabled to print layers from a 62 mm nozzle onto substrates
being disposed 6.5 mm away. It is further known that on substrates that
permitted substantial spreading of the deposited materials, neighboring drops
merge to form single larger shapes, whereas on other substrates the
individual dots would remain independent(3). Similar attempts to print layers on
the substrates with zirconia powder, using material with 14% ceramic content by
volume as well as with PZT, up to 40% ceramic particles by volume is also
known(4,5).
Three dimensional printing on metals and their alloys by direct process is known,
which includes copper, aluminum, tin and various alloys. More recently, several
research groups have demonstrated aluminum deposition (6,7). In one known
example, near-net shape components, with family simple shapes, have been
formed from AI2024 alloy printed from a 100 mm orifice. In another known
example, pressure pulses of argon gas in the range of 20-100 KPa were used to
eject droplets of molten aluminum at a rate of 1-5 drops per second. To achieve
this, the aluminum was melted at 750 degree C and the substrate to 300 degree
C. The nozzle orifice used was 0.3 mm in diameter, with a resulting droplet size
of 200-500 mm and a deposited line of width 1.00 mm and thickness 0.17 mm.
The final product was a near net shape part of density up to 92%. It is observed
from the prior art that printing is a viable process for three dimensional
prototyping and manufacturing (8).
OBJECTS OF THE INVENTION
It is therefore, an object of the invention to propose a process for application of
polymer, ceramic or metal coatings on a molting sheet substrate for line-wise
deposition of coating material.
Another object of the invention is to propose a process for application of
polymer, ceramic or metal coatings on a molting sheet substrate for line-wise
deposition of coating material, in which the liquid coating is dispensed from
multiple nozzles vertically disposed on the top of the moving sheet substrate.
A still another object of the invention is to propose a process for application of
polymer, ceramic or metal coatings on a molting sheet substrate for line-wise
deposition of coating material, in which irradiation light sources such UV or IR
radiations is used for solidification of the liquid a polymer which supplies the
energy that transforms a multifunctional prepolymer into a crosslinked polymer.
A further object of the invention is to propose a process for application of
polymer, ceramic or metal coatings on a molting sheet substrate for line-wise
deposition of coating material, which is enabled to print 3-D image, photograph,
logo, symbol, name and drawing on sheet surface.
A still further object of the invention is to propose a process for application of
polymer, ceramic or metal coatings on a molting sheet substrate for line-wise
deposition of coating material, in which different coating liquid and
corresponding sequence of deposition can be achieved.
SUMMARY OF THE INVENTION
Accordingly, there is provided a process for application of polymer, ceramic or
metal coatings on a molting sheet substrate for line-wise deposition of coating
material, comprising the steps of:
providing a substrate to be coated, the substrate being rotatable and
movable by an externally being rotatable and movable by an externally
disposed power source; providing a plurality of coating nozzles in spaced-
apart positions vertically disposed at specified height along the surface of the
substrate, the nozzles having orifices and jet spraying under venture effect
one of polymer, ceramic, and metal coating on the substrate; a drying system
to dry the coating layer immediately after application on the substrate,
wherein a line-wise deposition of the coating is achieved and wherein the
liquid polymer coating comprising multi-functional prepolymer is transformed
into a cross-linked polymer.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention, one of a polymer, ceramic or metal coating is
applied on cold rolled steel, galvanized steel, aluminum or aluminized steel,
using the concept of three dimensional printing technology, wherein the
coating heads having a plurality of nozzles disposed above the moving sheet
substrate for line-wise deposition of coating material. In the inventive
process, an use is made of a drying system such as ultraviolet/IR light to dry
the coating layer immediately after application on a steel substrate. Any
recoating process involves application of a fresh layer of liquid resin on top of
the preceding cured layer and then drying. A uniform coating or 3D image
can be created on the steel substrate by using the disclosed coating process.
The number of recoating steps depends on the final properties required.
The known process of three dimensional (3D) printing processes is herein
considered for polymer, ceramic or metal coatings application on sheet
substrate wherein the coating liquid is dispensed from multiple nozzles
positioned above the moving sheet substrate for deposition of coating
material. There is a uniqueness in the claimed process in as much as that in a
known 3D printing process, the substrate is kept in a static position and the
printing medium moves as opposed to claimed process, in which the
substrate is in motion and printing medium resides above the substrate.
Furthermore, the known 3D printing technology is a batch process whereas
the disclosed coating process is on-line. The sheet substrate such as cold
rolled steel, galvanized steel, aluminum or aluminized steel can be coated
with polymer, ceramic or metal coating.
REFERENCES
1. Polyjet technology-3 dimensional printing applications
http://www.2obiect.com
2. In-Vision 3D printer
http://www.cadem.com.tr/3dsvstems/invision/index.html.
3. Tay B, Edirisinghe MJ (2001) Investigation of some phenomena occurring
during continuous ink-jet printing of ceramics. J Mater Res 16(2):373-384.
4. Zhao X, Evans JRG, Edirisinghe MJ (2002) Direct ink-jet printing of vertical
walls. J Am Ceram Soc 85(8):2113-2115.
5. Wang T. Derby B (2005) Ink-jet printing and sintering of PZT. J. Am
Ceram Soc 88(8):2053-2058.
6. Liu Q. OrmeM (2001) On precision droplet-based net-form manufacturing
technology. Proc 1 MECH E Part B-J Eng Manufacture 215:1333-1355.
7. Cao W. Miyamoto Y (2006) Freeform fabrication of aluminum parts by
direct deposition of molten aluminum. J Mater Process Technol 173:209-
212.
8. I. Gibson, D.W. Rosen, and B. Stucker, Additive Manufacturing
Technologies, Spring Science + Business Media, LLC 2010.
WE CLAIM :
1. A process for application of polymer, ceramic or metal coatings on a
molting sheet substrate for line-wise deposition of coating material,
comprising the steps of:
- providing a substrate to be coated, the substrate being rotatable and
movable by an externally being rotatable and movable by an externally
disposed power source;
- providing a plurality of coating nozzles in spaced-apart positions vertically
disposed at specified height along the surface of the substrate, the
nozzles having orifices and jet spraying under venture effect one of
polymer, ceramic, and metal coating on the substrate;
- a drying system to dry the coating layer immediately after application on
the substrate, wherein a line-wise deposition of the coating is achieved
and wherein the liquid polymer coating comprising multi-functional
prepolymer is transformed into a cross-linked polymer.
2. The process as claimed in claim 1 wherein the coating comprising a polymeric
compound such as polyurethane, epoxy, polyethylene, polypropylene,
polyesters, polyimide, sol-gel and applied in layers and is cured by the drying
system such as UV/IR irradiation light radiations.
3. The process as claimed in claim 1, whererin a ceramic or metal-based
composite compound such as silica, silicon nitride, alumina, hydroxyapatite,
zirconate titanate oxides PZT, aluminum is applied in layers and is cured by
the drying system.
4. The process as claimed in claim 1, wherein a metal compound such as
stainless steel, tool steel, nickel-based alloys, titanium, and aluminum alloys,
zinc alloy is applied in layers.
5. The process as claimed in claim 1 wherein a uniform coating layer is applied
on the sheet surface the layer consists of single or multilayer depending on
final properties required.
6. The process claimed in claim 1, wherein 3D images such as, photograph,
logo, trade symbol, name, drawing is deposited on the sheet surface by
selectively using the different types of coating liquids including sequence of
their deposition.
7. The process as claimed in claim 1, wherein the coated material is further
subjected to heat treatment to obtain the desired mechanical properties or
stress relief.

ABSTRACT

The invention relates a process for application of polymer, ceramic or
metal coatings on a molting sheet substrate for line-wise deposition of
coating material, comprising the steps of: providing a substrate to be
coated, the substrate being rotatable and movable by an externally being
rotatable and movable by an externally disposed power source; providing
a plurality of coating nozzles in spaced-apart positions vertically disposed
at specified height along the surface of the substrate, the nozzles having
orifices and jet spraying under venture effect one of polymer, ceramic,
and metal coating on the substrate; a drying system to dry the coating
layer immediately after application on the substrate, wherein a line-wise
deposition of the coating is achieved and wherein the liquid polymer
coating comprising multi-functional prepolymer is transformed into a
cross-linked polymer.