U.S. patent application number 10/798467 was filed with the patent office on 2005-09-15 for thermal spray grit roller.
Invention is credited to Leung, Chi Kong.
Application Number | 20050202945 10/798467 |
Document ID | / |
Family ID | 34920275 |
Filed Date | 2005-09-15 |
United States Patent
Application |
20050202945 |
Kind Code |
A1 |
Leung, Chi Kong |
September 15, 2005 |
Thermal spray grit roller
Abstract
A thermal spray grit roller includes a roller shaft having an
outer periphery and a roller body connected to the outer periphery
of the roller shaft. A grit layer comprising a multiple individual
grit particles is deposited on the circumferential outer surface of
the roller body by a thermal spray process. A method for
manufacturing the thermal spray grit roller includes collecting raw
materials for use in the method, including at least one roller
subassembly, having a roller body connected to a roller shaft, and
the application material. The outer surface of each roller body is
degreased. Then, any portion of the roller body outer surface that
will not be covered by the grit layer is masked. Finally, the grit
layer is formed on the roller body outer surface with a thermal
spray process.
Inventors: |
Leung, Chi Kong; (Tin Shui
Wai, CN) |
Correspondence
Address: |
ALIX YALE & RISTAS LLP
750 MAIN STREET
SUITE 1400
HARTFORD
CT
06103
US
|
Family ID: |
34920275 |
Appl. No.: |
10/798467 |
Filed: |
March 11, 2004 |
Current U.S.
Class: |
492/37 ;
29/895.32 |
Current CPC
Class: |
B65H 2404/5331 20130101;
B65H 2402/80 20130101; C23C 4/134 20160101; G03G 2215/00683
20130101; Y10T 29/49563 20150115; B65H 2801/06 20130101; B65H
2401/12 20130101; B65H 27/00 20130101; B65H 2404/5212 20130101 |
Class at
Publication: |
492/037 ;
029/895.32 |
International
Class: |
B21B 001/40; E01C
019/23 |
Claims
1: A thermal spray grit roller comprises: a roller shaft having an
outer periphery; a roller body connected to the outer periphery of
the roller shaft, the roller body having a circumferential outer
surface; and a grit layer comprising a plurality of individual grit
particles deposited on the roller body outer surface by a thermal
spray process.
2: The thermal spray grit roller of claim 1 wherein the roller
shaft has a columnar-shape and the roller body is integrally formed
with the roller shaft.
3: The thermal spray grit roller of claim 1 wherein the roller
shaft has a columnar-shape and the roller body is fixedly mounted
to the roller shaft outer periphery.
4 (canceled)
5 (canceled)
6 (canceled)
7: The thermal spray grit roller of claim 1 wherein the grit
particles are each composed of an electrically conductive material
or a ceramic material.
8: The thermal spray grit roller of claim 7 wherein the
electrically conductive material is selected from aluminum,
aluminum alloy, zinc, zinc alloy, copper, brass, nickel, titanium,
carbon steel, stainless steel, chrome, iron, cobalt, molybdenum,
chromium carbide, and tungsten carbide.
9: The thermal spray grit roller of claim 7 wherein the ceramic
material is selected from aluminum oxide, chromium oxide, and
zirconium oxide.
10: A method for manufacturing a thermal spray grit roller
comprising the steps of: collecting raw materials for use in the
method, including at least one roller subassembly, comprising a
roller body connected to a roller shaft, and application material;
degreasing the outer surface of each roller body; masking any
portion of the roller body outer surface that will not be covered
by a grit layer; and forming a grit layer on the roller body outer
surface with a thermal spray process.
11: The method of claim 10 wherein the step of degreasing comprises
immersing the roller subassemblies in a tank containing
trichloromethane for 20 to 30 seconds and air drying the roller
subassemblies for substantially 60 seconds.
12: The method of claim 10 further comprising the step of
inspecting a representative sample of the rollers after forming the
grit layer.
13: The method of claim 10 further comprising the step of
inspecting the raw materials including ensuring that the
application material is the correct material; ensuring that the
dimensions of the roller shaft and roller body conform to
specification; and ensuring that the roller shaft and roller body
conform to cosmetic requirements.
14: The method of claim 10 wherein the step of masking comprises
masking the portions of the roller body outer surface with a
polyurethane protector.
15: The method of claim 10 further comprising the step of
sandblasting the outer surface of roller bodies composed of metal,
after the step of masking, to remove any oxidation.
16: The method of claim 15 wherein the step of sandblasting
includes: setting a sandblasting gun to 3 to 4.5 psi; and blasting
the roller body surface for 25 to 50 seconds with sand having a
particle size of #80 to #200.
17: The method of claim 15 wherein the step of sandblasting
includes sandblasting the roller body surface to produce a
roughness average of 0.2 to 1.0 Ra.
18: The method of claim 15 further comprising the step cleaning the
roller body surface after the step of sandblasting.
19: The method of claim 18 wherein the step of cleaning includes
sweeping the roller body surface with an air brush.
20: The method of claim 10 wherein the step of forming a grit layer
includes: installing electrodes or verifying that electrodes of the
application material are installed in an arc spray machine; setting
the arc spray machine output power; setting the arc spray machine
compressed air pressure; setting or verifying the gap between the
spray gun and the roller body surface; setting the spray gun feed
rate; setting the rotational speed of the roller; and energizing
the arc spray machine for a predetermined period of time, whereby
the arc spray machine deposits a grit layer having the specified
surface roughness and the specified thickness.
21: The method of claim 20 wherein the spray gun feed rate is set
at 0.2 to 0.5 m/min.
22: The method of claim 20 wherein the rotational speed of the
roller is set at 200 to 400 rpm.
23: The method of claim 20 wherein the gap between the spray gun
and the roller body surface is set in the range of 150 to 250
mm.
24: The method of claim 20 wherein the arc spray machine power is
set in the range of 25 to 35 volts and 50 to 300 amps and the
compressed air pressure is set in the range of 4 to 7 psi.
25: The method of claim 10 wherein the step of forming a grit layer
includes: installing or verifying the installation of the
application material and a bonding agent in a plasma spray machine;
setting the plasma spray machine output power; setting the plasma
spray machine gas pressure; setting or verifying the gap between
the spray gun and the roller body surface; setting the spray gun
feed rate; setting the rotational speed of the roller; and
energizing the plasma spray machine for a predetermined period of
time, whereby the plasma spray machine deposits a grit layer having
the specified surface roughness and the specified thickness.
26: The method of claim 25 further comprising the step of applying
an initial grit layer of the application material to the roller
body surface with an arc spray machine.
27: The method of claim 25 wherein the spray gun feed rate is set
at 0.2 to 0.5 m/min.
28: The method of claim 25 wherein the rotational speed of the
roller is set at 200 to 400 rpm.
29: The method of claim 25 wherein the gap between the spray gun
and the roller body surface is set in the range of 70 to 120
mm.
30: The method of claim 25 wherein the plasma spray machine power
is set in the range of 40 to 80 volts and 500 to 650 amps, the arc
gas pressure is set in the range of 60 to 180 psi, and the carrier
gas pressure is set in the range of 30 to 80 psi.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to paper feed mechanisms
for printers or the like. More particularly, the present invention
relates to a pressure contact roller for use in a feed mechanism
for advancing a sheet of paper to a recording position in a
printer.
[0002] In early computer printers, and the like, the paper, or
other print record medium, was incrementally stepped along a paper
path. In such a printer, one requirement was that the stepping be
precisely controlled to maintain proper registration of the lines
of print on the paper. Generally, this was accomplished by
providing the paper with a series of equally spaced holes along the
edges thereof and to provide the printer with a roller having
sprocket wheels with circumferentially spaced pins on the periphery
thereof. These sprocket wheels engaged the holes of the paper to
feed the paper while maintaining the required registration. To
allow continuous printing of multiple page documents, the paper was
provided as continuous fan-folded "ribbon" of paper. The paper
ribbon commonly had longitudinally spaced lateral lines of
perforations to facilitate separating the ribbon into individual
paper sheets. In addition, the paper ribbon often had
longitudinally extending lines of perforations at the margins of
the ribbon to facilitate removal of the side portions of paper
having the holes. However, the paper edge left by using the
perforations was rough compared to conventionally cut sheets of
paper and paper that did not have indexing holes along each edge
could not be used in these printers.
[0003] Friction feed rollers have substantially replaced sprocket
wheels in more recent computer printers, and the like. Generally,
the outer surface of the feed roller frictionally engage the paper
and the feed roller is rotated by a paper feed motor to advance the
sheet of paper to the print head. Pressure contact rollers are
rotatably disposed near the feed rollers, and are held in pressure
contact with outer surfaces of the corresponding feed rollers to
cooperatively advance a sheet of paper disposed between the
pressure contact rollers and the feed rollers.
[0004] The rollers are usually manufactured by forming a rod-like
roller shaft by machining or molding, and then integrally forming a
substantially cylindrical roller body made of an elastomer material
over an outer circumference of the roller shaft. Because the
recording surface of the sheet of paper contacts the outer surface
of the roller body, the roller body is required to be made of an
elastomer material that does not affect the recording surface.
[0005] Generally, the elastomer material used to produce
conventional rollers has a relatively short lifetime and is rather
sensitive to temperature variance. Temperature induced contraction
or expansion of the roller body has a deleterious effect on the
functional performance of the roller.
SUMMARY OF THE INVENTION
[0006] Briefly stated, the invention in a preferred form is a
thermal spray grit roller which includes a roller shaft having an
outer periphery and a roller body connected to the outer periphery
of the roller shaft. A grit layer comprising a multiple individual
grit particles is deposited on the circumferential outer surface of
the roller body by a thermal spray process.
[0007] The grit particles are each composed of an electrically
conductive material or a ceramic material. The electrically
conductive material may be aluminum, aluminum alloy, zinc, zinc
alloy, copper, brass, nickel, titanium, carbon steel, stainless
steel, chrome, iron, cobalt, molybdenum, chromium carbide, and
tungsten carbide. The ceramic material may be aluminum oxide,
chromium oxide, and zirconium oxide.
[0008] A method for manufacturing a thermal spray grit roller
comprises the steps of collecting raw materials for use in the
method, including at least one roller subassembly, having a roller
body connected to a roller shaft, and the application material. The
outer surface of each roller body is degreased. Then, any portion
of the roller body outer surface that will not be covered by the
grit layer is masked. Finally, the grit layer is formed on the
roller body outer surface with a thermal spray process.
[0009] The step of degreasing includes immersing the roller
subassemblies in a tank containing trichloromethane for 20 to 30
seconds and then air drying the roller subassemblies for
approximately 60 seconds.
[0010] The method may further comprise inspecting a representative
sample of the rollers after forming the grit layer.
[0011] The step of inspecting the raw materials includes ensuring
that the application material is the correct material, ensuring
that the dimensions of the roller shaft and roller body conform to
specification, and ensuring that the roller shaft and roller body
conform to cosmetic requirements.
[0012] For roller bodies composed of metal, the method further
comprises sandblasting the outer surface of the roller bodies,
after the roller bodies are masked, to remove any oxidation. The
sandblasting includes setting a sandblasting gun to 3 to 4.5 psi
and blasting the roller body surface for 25 to 50 seconds with sand
having a particle size of #80 to #200. More generally, the
sandblasting includes blasting the roller body surface to produce a
roughness average of 0.2 to 1.0 Ra. After sandblasting, the roller
body surface is cleaned with an air brush.
[0013] The grit layer may be formed by installing electrodes or
verifying that electrodes of the application material are installed
in an arc spray machine, setting the arc spray machine output
power, setting the arc spray machine compressed air pressure,
setting or verifying the gap between the spray gun and the roller
body surface, setting the spray gun feed rate, setting the
rotational speed of the roller, and energizing the arc spray
machine for a predetermined period of time, whereby the arc spray
machine deposits a grit layer having the specified surface
roughness and the specified thickness.
[0014] Alternatively, the grit layer may be formed by installing or
verifying the installation of the application material and a
bonding agent in a plasma spray machine, setting the plasma spray
machine output power, setting the plasma spray machine gas
pressure, setting or verifying the gap between the spray gun and
the roller body surface, setting the spray gun feed rate, setting
the rotational speed of the roller, and energizing the plasma spray
machine for a predetermined period of time, whereby the plasma
spray machine deposits a grit layer having the specified surface
roughness and the specified thickness.
[0015] An initial grit layer of the application material to the
roller body surface with an arc spray machine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The present invention may be better understood and its
numerous objects and advantages will become apparent to those
skilled in the art by reference to the accompanying drawings in
which:
[0017] FIG. 1 is a perspective view of a roller in accordance with
the invention;
[0018] FIG. 2 is an enlarged cross-sectional view taken along line
2-2 of FIG. 1;
[0019] FIG. 3 is a flow diagram of the thermal spray process for
making a roller in accordance with the invention;
[0020] FIG. 4 is a plan view, enlarged 200 times, of the thermal
spray grit surface produced by the process of FIG. 3;
[0021] FIG. 5 is a flow diagram of the arc spray process; and
[0022] FIG. 6 is a flow diagram of the plasma spray process.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0023] With reference to the drawings wherein like numerals
represent like parts throughout the several figures, a roller
having a thermal spray grit surface in accordance with the present
invention is generally designated by the numeral 10.
[0024] With reference to FIGS. 1 and 2, a first embodiment of the
subject roller 10 has a columnar roller shaft 12 formed by molding
or machining. The roller shaft 12 may be any material
conventionally utilized in the construction of printer roller
shafts. Over an outer periphery 14 of the roller shaft 12, a roller
body 16 having a cylindrical circumferential outer surface 18 is
formed integrally with the roller shaft 12 or fixedly mounted to
the roller shaft 12, depending on the materials utilized to
manufacture the roller shaft 12 and the roller body 16. The roller
body 16 may be ceramic, a polymeric material or metal, for example
stainless steel, copper or aluminum. The outer diameter of the
roller body 16 is larger than the outer diameter of the roller
shaft 12.
[0025] A layer of grit 22 is deposited on the outer surface 18 of
the roller body 16 such that the outer surface 24 of the roller 10
has an optimal coefficient of friction for engaging a paper sheet
being transported through the printer. As described below, the grit
layer 22 is formed by depositing individual grit particles 26 by
either an arc spray procedure or a plasma spray procedure.
Initially, the grit particles 26 are deposited on the outer surface
18 of the roller body 16, and then subsequent grit particles 26 are
deposited on the initial grit particles 26 to build the grit layer
22 to the desired thickness.
[0026] In the arc spray procedure 28, two wires are inserted into a
torch and brought into contact with each other at the nozzle. The
electrical load placed on the wires causes the tips of the wires to
melt where they touch. A carrier gas such as air or nitrogen is
used to strip the molten material off the wires as fine metal
particles and to transport the molten particles to the workpiece.
Since the electrodes must conduct electricity to form the arc, the
metal wires forming the electrodes must be composed of an
electrically conductive material. For example, aluminum, aluminum
alloy, zinc, zinc alloy, copper, brass, nickel, titanium, carbon
steel, stainless steel, or chrome. preferably, the metal wires are
composed of grade 316 stainless steel (SUS 316) which has high wear
resistance (providing accurate paper feeding and minimizing
compression set from the pinch rollers), has high corrosion
resistance (preventing rust formation from ink aerosol and
environmental humidity), and is highly conductive (facilitating
discharge of static electricity).
[0027] In the plasma spray procedure 30, a compressed gas (e.g.
argon, nitrogen, helium, or hydrogen) is passed through a torch. An
electrical field in the torch creates an electrical arc that
disassociates and ionizes the gases. Beyond the nozzle, the atomic
components recombine, giving off a tremendous amount of heat. In
fact, the plasma core temperatures are typically greater than
10,000.degree. C., well above the melting temperature of any
material. A powder including the application material and a bonding
agent is injected into this flame, melted (forming a plasma), and
accelerated to the workpiece. Since the application material is not
required to conduct an electrical current, electrically
non-conductive application materials may be used. For example,
aluminum oxide, chromium oxide, and zirconium oxide. Alternatively,
electrically conductive material may be used. For example,
aluminum, aluminum alloy, iron, copper, cobalt, molybdenum, nickel,
chromium carbide, and tungsten carbide.
[0028] The particle velocities for plasma are higher than for those
of arc spraying and result in coatings that are typically denser
and have a finer as-sprayed surface roughness. The tradeoff of
increased density, however, is that the maximum coating thickness
for a given material is usually reduced. As both metals and
ceramics can be effectively sprayed with this technique, plasma
spraying lends itself to automation and to reducing process
steps.
[0029] A grit layer 22 produced by either the arc spray procedure
28 or the plasma spray procedure 30 is superior to conventional
elastomeric roller bodies for a number of reasons. A metal or a
metal alloy can be used in either procedure 28, 30 and a ceramic
material may be used in the plasma spray procedure 30, providing
great versatility. The use of a metal coating provides a roller 10
that has close to zero compression set. The thickness of the grit
layer 22 may be controlled very tightly, either spray procedure 28,
30 providing a tolerance of +/-0.02 mm. The generation of the metal
particles may be adjusted in the arc spray procedure 28, allowing
the grit roughness to be controlled to provide ideal friction and
traction. Although the metal particles are molten material, the
overall arc spray procedure is performed in a relatively low
temperature, preventing temperature related damage to the roller
shaft 12 and roller body 16. Since the grit layer 22 may be
electrically conductive, the roller 10 is easily grounded,
preventing static charge accumulation that attracts dust particles.
For most printer uses, the advantages provided by an electrically
conductive grit layer 22 militate against the use of an
electrically non-conductive application material. The cost of
rollers 10 produced by the arc spray procedure 28 is low relative
to the cost of rollers having a conventional rubber surface, for
example ethylene propylene diene monomer (EPDM), or epoxy/PU grit
coating.
[0030] With reference to FIG. 3, the raw materials 32 used in the
subject thermal spray process 34 includes a roller subassembly,
comprising the assembled/integrally manufactured roller shaft 12
and roller body 16, and the application material to be sprayed on
the roller body 16. These raw materials are initially inspected 36
to ensure that the application material is the correct material,
that the dimensions of the roller shaft 12 and roller body 16
conform to specification and cosmetic requirements.
[0031] The outer surface 18 of the roller bodies 16 of conforming
roller subassemblies are then degreased 38 with a conventional
degreasing agent. Any oil film remaining on surface 18 will
interfere with deposition of the initial grit particles 26 onto the
roller body surface 18, allowing the affected portions of the grit
layer 22 to peel off during operation of the printer. Accordingly,
care must be taken that the degreasing agent is properly applied
and that the roller body surface 18 is completely free of oil.
preferably the roller subassemblies are immersed in a degreasing
tank containing trichloromethane for 20 to 30 seconds and then air
dried for approximately 60 seconds.
[0032] After the entire outer surface 18 of the roller body 16 is
degreased 38, those portions of the outer surface 18 that will not
be covered by the grit layer 22 are masked 40, preferably with
polyurethane protector.
[0033] If the roller body 16 is composed of metal, the outer
surface 18 will commonly have an oxidation layer. Since such an
oxidation layer would interfere with the initial grit particles 26
adhering to the outer surface 18, the outer surface 18 is
sandblasted 42 to remove any surface oxidation that may be present
in the non-masked area. The particle size of the sand used in the
blasting procedure 42 is dependent on the composition of the roller
body 16. However, a particle size of #80 to #200 will generally be
sufficient. Preferably, the sandblasting gun is set to 3 to 4.5 psi
and the surface 18 of the roller body 16 is blasted for 25 to 50
seconds to produce a roughness average of 0.2 to 1.0 Ra.
[0034] Any sand dust remaining on the roller body surface 18 after
the sandblasting procedure 42 is removed by "sweeping" 44 the
roller body surface 18 with an air brush created by an air gun
operated at 2 to 3 psi. Generally sweeping 44 the roller body
surface 18 for approximately 2 seconds is sufficient to remove the
sand dust, that would otherwise create pin holes in the grit layer
22. After the sandblasting procedure 42 is completed, the sweeping
procedure 44 is conducted and the spray procedure 28, 30 is begun
as expeditiously as possible to prevent the formation of new oxides
on the roller body surface 18.
[0035] With additional reference to FIG. 6, the arc spray procedure
28 begins with determining 46 which application material will be
used to form the grit layer 22 and either installing electrodes 48
of the proper material or verifying that electrodes of the proper
material are already installed. The arc spray procedure 28 can be
controlled to produce a specified grit layer thickness and a
specified grit layer roughness. The rate at which the application
material is deposited on. The roller body surface 18 determines the
surface roughness of the grit layer 22, with the roughness
increasing as the application material is deposited more quickly.
The rate of application material deposition is controlled by the
output power of the arc spray machine and/or the pressure of the
compressed air used to transport the spray particles from the arc
spray machine to the roller body surface 18. Therefore, the next
steps in the arc spray procedure 28 require setting the arc spray
machine output power 50 and the compressed air pressure 52. These
steps 50, 52 may be performed simultaneously or serially.
[0036] With respect to the output power of the arc spray machine,
the intensity of the electrical arc increases as the output power
is increased. The greater the intensity of the electrical arc, the
faster the application material of the electrodes is melted and
ultimately deposited onto the roller body surface 18. The flow of
compressed air through the arc spray machine acts to cool the
electrodes. Accordingly, increasing the pressure/flow rate reduces
the rate at which the electrodes are melted for any given arc spray
machine power level and reducing the pressure/flow rate increases
the rate at which the electrodes are melted for any given arc spray
machine power level. Preferably, the arc spray machine power is in
the range of 25 to 35 volts and 50 to 300 amps and the compressed
air pressure is in the range of 4 to 7 psi.
[0037] The thickness of the grit layer 22 is controlled by the feed
speed of the spray gun. As the feed speed slows down, more grit
particles 26 can be deposited onto the roller body surface 18 to
increase the thickness. The distance between the spray gun and the
roller body surface 18 and the rate at which the roller 10 is
rotated as the application material must also be controlled.
Therefore, the gap between the spray gun and the roller body
surface 18 must be set or verified to be correct 54, the spray gun
feed rate must be set 56, and the rotational speed of the roller
must be set 58 before operation of the arc spray machine is
initiated 60. Generally, a spray gun feed rate of 0.2 to 0.5 m/min
produces a grit layer thickness of 3 to 10 .mu.m per traverse when
the roller body 16 is rotated at 200 to 400 rpm. Preferably, the
distance between the spray gun and the roller body surface 18 is
set in the range of 150 to 250 mm. After all of the above-discussed
parameters have been set, the arc spray machine is energized for a
predetermined period of time 62 to deposit a grit layer 22 having
the specified surface roughness and specified thickness.
[0038] With additional reference to FIG. 7, an initial grit layer
22 may be applied 64 to the roller body surface using the arc spray
procedure 28, as a "primer" for a subsequent grit layer 22 that is
applied by the plasma spray procedure 30. Both an application
material and a bonding agent must be selected 66, 68 and then
installed or verified to be installed 70 in a feed hopper. During
the plasma spray procedure 30, particles of the bonding agent (e.g.
titanium oxide) are melted at an extremely high temperature. The
melted boding agent particles and grit particles composed of the
application material are then sprayed on the roller body surface
18. Since the grit particles are not melted, the roughness and
thickness of the grit layer is very much determined by grit
particle size, not so much by the output power and feeding speed.
Simply put, the bigger the particle size, the greater the roughness
and thickness.
[0039] Similar to the arc spray procedure 28, the operator must set
the output power 72, set an arc gas/carrier gas pressure 74, set
the spray gun feed rate 76, set the roller rotational speed 78, and
verify 80 the distance of the gap between the roller body surface
18 and the spray gun. Generally, a spray gun feed rate of 0.2 to
0.5 m/min produces a grit layer thickness of 3 to 10 .mu.m per
traverse when the roller body 16 is rotated at 200 to 400 rpm.
preferably, the distance between the spray gun and the roller body
surface 18 is set in the range of 70 to 120 mm. preferably, the
plasma spray machine power is in the range of 40 to 80 volts and
500 to 650 amps, the arc gas pressure is in the range of 60 to 180
psi and the carrier gas pressure is in the range of 30 to 80 psi.
The application material/boding agent feed rate is preferably set
to 20 to 30 g/min. After all of the above-discussed parameters have
been set, the plasma spray machine is energized 82 for a
predetermined period of time 84 to deposit a grit layer 22 having
the specified surface roughness and specified thickness.
[0040] Generally, after the arc spray procedure 28 or the plasma
spray procedure 30 has been completed 86, the masking is removed
92. A statistically representative sample of the rollers 10 is
inspected 88. Such inspection 88 generally includes measurement of
the diameter and run out of the roller body 16 by laser micrometer.
The roughness of the roller body surface 18 is measured with a
roughness tester and the coefficient of friction of the roller body
surface 18 is measured. Finally a visual inspection is conducted
and the finished product is shipped 90 by conventional means.
[0041] It should be appreciated that the plasma spray procedure 30
is more expensive to perform than the arc spray procedure 28 and
the grit layer 22 produced by the arc spray procedure 28 is more
than adequate for use in modern printers. Table 1 provides a
comparison of a thermal spray grit roller 10 in accordance with the
invention with several conventional rollers intended for use in
printers.
[0042] While preferred embodiments have been shown and described,
various modifications and substitutions may be made thereto without
departing from the spirit and scope of the invention. Accordingly,
it is to be understood that the present invention has been
described by way of illustration and not limitation.
1 TABLE 1 Grit Roller (Inorganic Particles w/ EPDM Rollers Grit
Rollers (aluminum & adhesive) binder) JP 2,512,332 Grit Roller
(Arc Spray) Manufacturing Process Either molded or extruded EPDM
cut in Apply adhesive on shafts, add grit Use melamine resin,
phenol, Using arc spray technology to coat length, then mounted on
shafts particles, then spray coat another layer polyethylene, or
polyamide as binder; SUS316 or any other conductive of adhesive
(could be epoxy, PU or any mix with inorganic particles via
injection materials on shafts to achieve the other bonding agents)
to hold particles process to mold in shape. Shot blast desire grit
surface in place. the surface to expose inorganic particle on
surface. Manufacturing Costs Very expensive if it is molded.
Cutting Total of 3 layers in the coating process. Tooling up for
molds could be really One of the least expensive method is costs or
cutting process could be Costly because staging (curing) is
expensive especially when we do high done correctly. Also very
flexible expensive & tedious if it is extruded required ideally
for each process volume production. Leadtime for hard because there
is not hard tooling. Start EPDM; especially when the specs for
tooling is another issue as well up time very short too.
perpendicularity and length tolerance is tight Heat Resistance of
Maximum temperature is 100.degree. C. or Around 100.degree. C. or
less Around 100.degree. C. or less The highest of all four, over
800.degree. C. Coating below Wear Resistance of Moderate Moderate,
grit particles could fall off High Very High Coating easily even if
it is bonded correctly. Corrosion Resistance of Very High High Very
High Very High Coating Tensile Bond Strength N/A Lowest of all four
Moderate Highest of all three, at 6,735 psi of Coating Compression
Set of Could be severe depending on the Very minimum Very minimum
Lowest of all four. Practically zero Coating hardness (shore) of
EPDM cots simply because SUS316 is rock hard metal Conductivity of
Coating Not Conductive, extremely bad. Paper Not Conductive. Paper
dust Not conductive unless conductive Highly conductive, merely
0.46 Ohm. dust accumulation could occur; accumulation could occur,
which particle is added in binder, but this All static will be
grounded to eliminate eventually reduce the traction on rollers
reduces the friction & traction of rollers. could be costly if
so. paper dust formation or accumulation. This will ensure high
traction on rollers at all times. Roughness Control in Moderate
Difficult to control due to the nature of Moderate Repeatability is
very high. Roughness Manufacturing manufacturing process. Grit
particles range can be kept at around Ra 3 to Ra could stack on one
another. 10, depending how the spray machine is set up. Thickness
Control in Moderate. Minimum thickness Difficult to control due to
the nature of Moderate, may be around +/-0.03 mm Repeatability is
very high. Minimum Manufacturing tolerance is around +/-0.03 mm
manufacturing process. Grit particles could stack thickness
tolerance can be kept at +/-0.01 mm on one another. RoHS
Requirement No hazardous material in EPDM Contains lead, not
allowed in most Contains lead, not allowed in most No hazardous
material in SUS316 European countries. European countries.
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