Note: Descriptions are shown in the official language in which they were submitted.
CA 02419732 2003-02-17
Tr ans 1 at i on o f Sp a c i f i c at i on
PCT/JPO1/07591
Our Ref . HNP0034
Aqueous Lubricant Of One Process Type Used For High
Efficient Cold Forging
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I
AQUEOUS LUBRICANT OF ONE PROCESS TYPE USED FOR HIGH EFFICIENT
COLD FORGING
F I ELD OF THE I NVEN'T I ON
In recent years, important parts for transportation
machineries are often manufactured by applying cold forging of
more than 70°~ of reduction area at one stroke to a steel of
having the tensile strength of more than 300 N/mmz. This cold
forging process is usually called as "high efficient cold
forging'. The present invention is related to a process to
form a lubricative coating layer having excellent performance
as lubricant onto the surface of a metallic material to be
subjected to the high efficient cold forging without any
previous chemical treatment. The present invention is related
also to an aqueous lubricant of one process type used for high
efficient cold forging, which facilitates to simplify the
conventional lubricant layer forming processes, that is, to
minimize space area required for forming the lubricative
coating layer and not to increase industrial waste products.
PRIOR ART
Generally, in cold forging of metallic material, such as
steel and stainless steel, coating layer is formed onto the
surface of a metallic material. The coating layer may prevent
a direct contact of the metallic material with a forging tool,
and may decrease a surface defects of burning and biting of the
metallic material which may arise by direct contact with the
forging tool.
There are two types of the coated layers to be formed onto
the surface of a metallic material, one of which is the type
that a lubricant is being adhered directly onto the surface of
the metallic material and the other is the type that a
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2
lubricant is being used onto the chemical layer being formed
previously over the surface of the metallic material.
The lubricative coating formed by being adhered directly
onto the surface of a metallic material has less adhesive
performance than the lubricative coating by being used
lubricant on to the chemical layer formed previously over the
surface of the metallic material, and therefore, the former
type is generally used for the cold forging with less amount
of deformation.
In case of the latter type, the chemical layer is firstly
formed on the surface of a metallic material through a chemical
process such as phosphate layer forming process and oxalate
layer forming process, which generally form chemical layer
suitable as a carrier of a lubricant, and the lubricant having
high lubricative property is used on to the chemical layer. In
this type, the formed film has a bilayer structure consisting
of a chemical layer as a carrier and a lubricant layer, which
has high resistant property against surface defects.
From this reason, this type has been widely employed in the
field such as wire drawing, tube drawing and cold forging.
Particularly, in the cold forging where severe deformation is
required, a process firstly forming the chemical layer
comprising phosphate or oxalate and then using a lubricant onto
the chemical layer is popularly employed.
The lubricant applied onto the chemical layer may be
divided into major two groups in terms of the usage. The first
group includes a lubricant to be mechanically adhered onto the
chemical layer and the second group includes a lubricant which
reacts with the chemical layer.
The first group of lubricant includes one prepared by using
mineral oil, vegetable oil or synthetic oil as base oil and
containing an extreme pressure additive in the base oil and
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one prepared by dissolving a solid lubricant, such as graphite
and molybdenum disulfide, together with a binder component into
the water. These lubricants may have advantage of easy for
controlling the solution since they can be used simply by means
of spray coating and dipping coating, however, as they have
just a low lubricative properties, they tend to be used for a
case where less amount of deformation of metallic material is
required.
On the other hand, in the second group of lubricant, a
reactive soap such as sodium stearate is used for a cold
forging where particularly high lubricative property is
required. The reactive soap reacts with the chemical layer and
provides a layer of high lubricative property.
However, since the reactive soap gives a chemical reaction,
control of the composition of the solution, temperature control
for the chemical reaction and renewal control of the
deteriorated solution, etc. are very important during the
process. Further, for example, in the reaction of the
phosphate layer with reactive soap, insoluble matter are
produced in the solution along with the formation of
lubricative layer. These insoluble matter are called as sludge,
which is troublesome since it is required to be regularly
excluded from the solution.
Further, the waste water arising in the formation process
of the phosphate layer is containing the phosphate compounds.
Such waste water should be appropriately treated in order to
remove its contained phosphate compounds. In most case, such
waste water containing phosphate compounds is subjected to
neutralization with slaked lime to precipitate the phosphate.
The precipitated phosphate compounds is separated from water
and is discarded as industrial waste together with the sludge
described above.
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Recently, it is a big issue to reduce waste products from
the industries for global environmental protection, and
industrial waste containing phosphate compounds has been
considered as serious problem in view of environmental
protection. And therefore, new processes which do not produce
waste products are highly desired.
Further, in the conventional process that produces a
phosphate layer and uses a reactive soap on the phosphate layer,
simplification and improvement of the process is required,
since it requires wide area for the processing plant, greater
time and complex control of the process. For example, in the
process of producing the phosphate layer, frequent analysis of
the phosphating solution on its free acidity, total acidity and
concentration of accelerator has to be carried out by means of
titration and the like. Further, in the reactive soap
application process, analysis of free acidity and concentration
of its constituent are regularly and manually carried out.
In order to solve the problems as described above, JP52-
20967A, wherein a lubricant composition containing water
soluble polymer or its aqueous emulsion as the base component,
a solid lubricant and a film-forming agent is disclosed.
However, no composition which has the same effect as the
conventional process of using a chemical layer and a reactive
soap has been obtained.
In order to solve the problems described above, another
prior art of "Aqueous lubricant used for cold working of
metallic material" disclosed in JP10-8085A can be cited. This
prior art relates to an aqueous lubricant used cold forging of
metallic material in which (A) water soluble inorganic salt, (B)
solid lubricant, (C) at least one oil selected from a group
consisting of chemical oil, animal oil, vegetable oil and
synthetic oil, (D) surface active agent and (E) water are well
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dispersed and emulsified homogenously.
This prior art is related to an aqueous non-reactive type
lubricant, and is aiming at simplifying the conventional three
processes of phosphate layer formation, water rinsing and
reactive soap application. That is, in this process, the
lubricant film is formed directly on the surface of the
metallic material by contacting the metallic material with the
aqueous lubricant of one process type by means of dipping or
the like, without forming any chemical layer previously on the
surface of the metallic material. This type of lubricant is
generally called as lubricant of one process type.
However, the lubricant according to this prior art is too
unstable to use in an industrial scale since it contains
emulsified oil component, and it is not steady to show a high
lubricative properties in high efficient cold forging.
As another prior art, an invention of "A lubricant
composition used for cold working of metallic materials" shown
in JP2000-63380A can be cited. This prior art is directed to a
lubricant comprising (A) synthetic resin, (B) water soluble
inorganic salt and water, wherein the rat io of (B) / (A) by
weight in solid state is in a range from 0. 25/1 to 9/1 and the
synthetic resin is either dissolved or dispersed in the
composition. However, this composition is also not steady to
show a high lubricative properties in high efficient cold
forging.
DISCLOSURE OF THE INVENTION
Therefore, it is an object of the present invention to
solve the problems of the conventional art as described above
and to provide a new aqueous lubricant of one process type used
for high efficient cold forging, which is being suitable for
manufacturing of an important parts of transportation
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machineries, which is being simplified the operation without
requiring any previous chemical treatment to form a coating
layer and is favorable for keeping of good global environment.
The invention of the present invention have been made by
investigation for solving the problems described above and have
found that a suitable aqueous lubricant of one process type is
obtainable by combining an water soluble inorganic salt, wax
and metal salt of a fatty acid in an aqueous solution at a
specific combining rate.
The aqueous lubricant of the present invention requires
only one step of applying the lubricant and does not require 3
steps consisting of chemical reaction for phosphate layer
formation, water rinsing and application with a reactive soap.
These 3 steps are required in the conventional process. Also,
the aqueous lubricant of the invention is a simplified process
and may decrease to produce industrial waste than the
conventional processes.
namely, the present invention is an aqueous lubricant of
one process type used for high efficient cold forging
characterized in that the aqueous lubricant comprises (A) a
water soluble inorganic salt, (B) wax and (C) a metal salt of a
fatty acid, wherein these component are dissolved or dispersed
in an aqueous solution and the ratio by weight in solid state
of (B)/(A) is in a range of 0. 60 ~ 0. 70 and the ratio by weight
in sol id state of (C) / (A) is in a range of 0. 1 ~ 0. 3. And the
lubricant of the present invention is suitable for
manufacturing an important parts of transportation machineries.
The preferable water soluble inorganic salt may be selected
from a group consisting of sulfate, silicate, borate, molybdate
and tungstate, and the wax is preferably a synthetic wax being
dispersed in water and having a melting point in a range of 70
~- 150°C. Further, the metal salt of a fatty acid is preferably
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a compound obtained by reacting saturated fatty acid of C12
C26 with at least one metal selected from a group consisting of
zinc, calcium, barium, aluminum, magnesium and lithium.
BRIEF DESCRIPTION OF DRAWINGS
Fig.l is a view showing the dimensional accuracy in cold
forging process 2 shown later in the embodiment.
MODES FOR CARRYING OUT THE INVENTION
Now, the present invention is explained further in detail.
The water soluble inorganic salt (A) used in the aqueous
lubricant of the present invention is contained in order to
give hardness and strength to the lubricative coating layer
formed on the surface of the metallic material. The water
soluble inorganic salt having such performance is required to
have a property to be homogeneously dissolved in the aqueous
lubricant and to form a strong lubricative coating layer when
drying. As the inorganic salt giving such property, it is
preferable to use at least one selected from a group consisting
of sulfate, si 1 icate, borate, molybdate and tungstate.
As the examples for the water soluble inorganic salt
described above, sodium sulfate, potassium sulfate, potassium
silicate, sodium borate (sodium tetraborate), potassium borate
(potassium tetraborate), ammonium borate (ammonium tetraborate),
ammonium molybdate, sodium molybdate and sodium tungstate may
be given. Any of these salts may be used either alone or in
combination of 2 or more salts.
As the wax (B), it is preferable to use a synthetic wax,
though there is no specific limitation in the structure and the
type. The wax may melt by a heat generated during the plastic
deformation in cold forging, thereby improving the lubricative
property of the lubricative coating layer. From this reason,
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it is preferable having a melting point in a range of 70 to
150°C and being stable in aqueous lubricant so as to perform the
preferable lubrication at the initial stage of the cold forging.
The practical examples for the wax may include
microcrystalline wax, polyethylene wax, polypropylene wax and
the like. These waxes are preferably contained in a form of
water dispersion or water emulsion to the aqueous lubricant.
The (B)/(A), namely the ratio by weight in solid state of the
wax (B) relative to the water soluble inorganic salt (A) is
preferably in a range of 0. 6 ~ 0.7. In high efficient cold
forging, which is a hard process, there is possibility that the
lubricative performance of the lubricative coating layer may be
insufficient when the ratio described above is less than 0.6,
while the adhesive performance of the lubricative coating layer
may be insufficient when said ratio is more than 0.7.
The metal salt of a fatty acid (C) used in the present
invention is for providing lubricative performance, and as the
metal salt of a fatty acid, though there is no specific
limitation in the type, it is preferable to use a product
obtained by reacting saturated fatty acids of C12 ~ C26 with at
least one metal selected from a group consisting of zinc,
calcium, barium, aluminum, magnesium and lithium.
However, it is more preferable to use any of calcium
stearate, zinc stearate, barium stearate, magnesium stearate
and 1 ithium stearate. The metal salt of a fatty acid used in
the present invention exists in an aqueous lubricant in
dispersed from, and a known surface active agent may be used
when required.
The (C)/(A), namely the ratio of the aqueous inorganic salt
(A) and the metal salt of a fatty acid (C) is set at a rate
ranging fromØ 1 to 0.3 by weight as the solid state. Under a
severe working condition like the high efficient cold forging,
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the knockout property of the processed parts may be
insufficient when said ratio is less than 0. 1. I-Iowever, under
a severe working condition like high efficient cold forging,
the accuracy of dimension of the obtained cold forged parts
could be insufficient when said ratio is more than 0.3.
When a surface active agent is required for dispersing the
metal salt of fatty acid and the wax in the aqueous lubricant,
any surface active agent of nonionic, anionic, amphoteric and
cationic type may be used. The nonionic surface active agent
includes, but not specifically limited to, polyoxyethylene
alkyl ester, polyoxyalkylene (ethylene or propylene) alkyl
phenyl ether, polyoxyethylene alkyl ester comprising
polyethylene glycol (or ethylene oxide) and higher fatty acid
(C12 N C18, for example), polyoxyethylene sorbitan alkyl ester
comprising sorbitan, polyethylene glycol and higher fatty acid
(C12 ~ C18, for example).
The anionic surface active agent includes, but not
specifically limited to, fatty acid salts, sulfuric esters,
sulfonates, phosphoric esters and dithiophosphoric esters. The
amphoteric surface active agent includes, but not specifically
limited to, carboxylates either in amino acid configuration or
betaine configuration, sulfuric esters, sulfonates, phosphoric
esters. The cationic surface active agent includes, but not
specifically limited to, amine salts of fatty acids, quaternary
ammonium salts and the like. Each of these surface active
agent may be used either alone or in combination of two or more
of them
The aqueous lubricant of one process type of the present
invention is used for high efficient cold forging for metallic
materials where more than 70°~ of section area reduction rate
are given at one stroke. The important parts for
transportation machineries used for automobiles and motorcycles,
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such as power train and chassis may be produced preferably by
applying the aqueous lubricant of the present invention. The
shape of the cold forging products is not particularly limited
to cylindrical shape and is also applicable foe processing of
more complicated configuration, such as gears and gear shafts.
Regarding the process to apply the aqueous lubricant of the
present invention to the metallic material, though it is not
specifically limited to, dipping method can be employed. The
aqueous lubricant may satisfactorily be applied when the
surface of the metallic material is fully covered with the
aqueous lubricant by any method. After the coating, it is
required to dry the coated aqueous lubricate.
The preferred coating operation can be given as below.
1) Shot blasting
2) Rinsing with hot water(Removal of soiled matter such as iron
powder and heating the metallic material) . 70 ~ 90°C, 1 ~ 3
minutes
3) Application of the aqueous lubricant . 50 ~ 70°C, dipping for
1 ~ 3 seconds
4) Drying: By air blowing under ambient temperature, 1~2
minutes
5) Cold forging
The weight of the formed lubricative coating layer (the
amount of the coating) onto the surface of the metallic
material is an important factor since it greatly affects the
processing performance, such as lubricative performance and
resistance to burning and biting. The weight of the formed
coating layer may be calculated based on the weight difference
between before and after the formation of the coating layer and
the coated area of the metallic material.
Weight of the lubricative coating layer =(Weight after the
formation of the coating layer - Weight before the formation of
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the coating layer)/(Area of the metallic material)
The weight of the formed lubricative coating layer suitable
for the following cold forging process, it is preferable to be
in a range of 5 ~15 g/cm'.
When the weight of the formed coating layer is less than 5
g/cma, sufficient lubricative performance cannot be provided,
and causing burning defects during the high efficient cold
forging. Whereas, when the weight of the formed coating layer
exceeds 15 g/cma,exfoliated lubricant film(dregs) may tend to
remain in the cold forging mold, and the dregs in the cold
forging mold may adversely affect the dimension accuracy of the
cold forged products by forming a partial underfill portion of
the forged products. The concentration of the constituent of
the aqueous lubricant can be controlled so as to adjust the
weight of the formed lubricative coating layer to be in the
range described above.
EMBODIMENT EXAMPLES AND COMPARATIVE EXAMPLES [I]
Now, the present invention is further explained with
referring Embodiment Examples and Comparative Examples given in
the following.
GMetallis materials
60,000 pieces of steel bar for counter shaft . Diameter 50 mm,
length 140 mm.
Grade of steel . JIS G 4105 SCM420.
Surface pretreatment . Shot blasted aiming at removing scales
for 14 minutes by using shot balls of 0.5mm diameter.
<Lubrication process A . One process typ a
1) Washing with hot water of 80°C . For removal of shot blast
powder and preliminary heating
2) Lubrication process . Dipping for 1 min. into a lubricant
of 60°C.
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3) Drying . Air blowing under room temperature for 1 min.
-Total time (Time for processing + Time for transportation) for
lubrication process A . 2 minutes and 30 seconds
Total plant area necessary for lubrication process A . 9 m'
<Lubrication process B . Conventional type(phosphate layer +
React ive soap) 7
1) Degrease by alkal i degreasing agent . (Trademark . Parclean
357, manufactured by Nippon Parkerizing Co.,Ltd), being
diluted to 3% aqueous solution, 80~, 10 minutes
2) Washing with water . tap water, room temperature, 5
minutes
3) Washing with acid . 10°~ aqueous solution of hydrochloric
acid, room temperature, 5 minutes
4) Washing with water . tap water, room temperature, 5
minutes
5) Washing with water . tap water, room temperature, 5
minutes
6) Chemical treatment by dipping in the phosphate film forming
solution . Trademark . Palbond L3675XHM (manufactured by
Nippon Parkerizing Co.,Ltd), being diluted to 1°~ aqueous
solution, 80°C, 10 minutes
7) Washing with water . tap water, room temperature, 5
minutes
8) Washing with water . tap water, room temperature, 5
minutes
9) Treatment with reactive soap . (Trademark . Paloob 236H,
manufactured by Nippon Parkerizing Co.,Ltd.), being diluted
to 1% aqueous solution, 90°C, 10 minutes
10) Washing with hot water . tap water, 80°x, 5 minutes
11) Drying . Air blowing under room temperature, 10 minutes
Total time (Time for processing + Time for transportation)
necessary for lubrication process B . 60 minutes
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Total plant area necessary for lubrication B . 90 m'
<Cold forging process 1 . Resistance to burning>
Section area reduction rate by forward extrusion . 77%
Cold forging mold . ultrahard alloy, high speed steel (Heis)
Cold forging punch . high speed steel (Heis)
Cold forging speed . 0.078 m/sec
<Cold forging process 2 . Dimensional accuracy by resistance to
under fill>
A shaft specimen having a diameter of 27 mm produced in the
forging process 1 was subjected to annealing and then cold
forged by forward extrusion as shown in Fig.l and the diameter
at A part of Fi g. 1 was measured. '
<Evaluation>
~ Resistance to burning in cold forging process 1 . Surface
defects on the cold forging tool and cold forged products
were visually observed. If surface defects are observed, it
is not acceptable.
~ Dimensional accuracy in cold forging process 2 . The diameter
of the A part (Fig. 1) was measured. If cold forging is in
good accuracy, the diameter of the A part is 27 mm If the
diameter is less than 27 mm, it is in a state so-called "non-
accurate", which is not acceptable. A diameter of, 27 mm was
expressed as "o mm", and for example, a measured diameter of
26. 5 mm is expressed as "-0. 5 mm".
~ Simplification of the lubrication process . Evaluation was
made based on the number of treatment steps in lubrication
process and the total plant area necessary for lubrication
process. Less treatment step and less area are preferable.
~ Environmental protection . Amount of waste products (drainage,'
sludge, etc) generated in treatment of 6,000 pieces of
specimen was measured. Less amount for the treatment is
preferable.
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<Embodiment Example 17
A lubricant 1 as below was used, and coating was carried
out according to lubrication process A (one process type).
Lubricant 1 .
Aqueous inorganic salt . Sodium tetraborate
Wax . Polyethylene wax(1°~ by weight of nonionic surface
active agent was added for improving dispersion).
Metal salt of fatty acid . Calcium stearate
Sol id component rat io . (B) / (A) . 0. 70
So 1 i d component rat i o . (C) / (A) . 0. 1
Weight of formed coating layer, g/cm2 . 15
<Embodiment Example 2~
A lubricant 2 as below was used, and coating was carried
out according to lubrication process A (one process type).
Lubricant 2 .
Aqueous inorganic salt . Potassium tetraborate
Wax . Microcrystalline wax(1% by weight of nonionic surface
active agent was added for improving dispersion).
Metal salt of fatty acid . Calcium stearate
So 1 i d component r at i o . (B) / (A) . 0. 6
So 1 i d component r at i o . (C) / (A) . 0. 3
Weight of formed coating layer (g/cm2) . 15
<Embodiment Example 3~
A lubricant 3 as below was used, and coating was carried
out according to lubrication process A (one process type).
Lubricant 3 .
Aqueous inorganic salt . Sodium tetraborate
Wax . Polyethylene wax (1% by weight of nonionic surface
active agent was added for improving dispersion).
Metal salt of fatty acid . Calcium stearate
So 1 i d component r at i o . (B) / (A) . 0. 6
So 1 i d component rat i o . (C) / (A) . 0. 2
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Weight of formed coating layer (g/cmz) . 10
<Embodiment Example 4J
A lubricant 4 as below was used, and coating was carried
out according to lubrication process A (one process type).
Lubricant 4 .
Aqueous inorganic salt . Sodium tetraborate
Wax . Paraffin wax (1% by weight of nonionic surface active
agent was added for improving dispersion).
Metal salt of fatty acid . zinc stearate
So 1 i d component r at i o . (B) / (A) . 0. 7
So 1 i d component r at i o . (C) / (A) . 0. 2
Weight of formed coating layer (g/cmz) . 12
<Comparative Example 1~
A lubricant 5 as below was used, and coating was carried'
out according to lubrication process A (one process type).
Lubricant 5 .
Aqueous inorganic salt . Sodium tetraborate
Wax . Paraffin wax (1% by weight of nonionic surface active
agent was added for improving dispersion).
Metal salt of fatty acid . Calcium stearate
Sol id component rat io . (B) / (A) . 1. 0 (Out of the scope of
the present invention)
So 1 i d component rat i o . (C) / (A) . 0. 2
We i ght of coated f i lm (g/cm2 ) . 10
<Comparative Example 2~
A lubricant 6 as below was used, and coating was carried
out according to lubrication process A (one process type).
Lubricant 6:
Aueous inorganic salt . Sodium tetraborate
Wax . Polyethylene wax (1°,6 by weight of nonionic surface
active agent was added for improving dispersion).
Metal salt of fatty acid . Calcium stearate
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So 1 i d component r at i o . (B) / (A) . 0. 7
Sol id component rat io . (C) / (A) : 0. 5 (Out of the scope of
the present invention)
Weight of coated film (g/cm2) . 5
<Comparative Example 3~
A lubricant 7 as below was used, and coating was carried
out according to lubrication process A (one process type).
Lubricant 7 .
Aqueous inorganic salt . Potassium tetraborate
Wax . Polyethylene wax (1°~ by weight of nonionic surface
active agent was added for improving dispersion).
Metal salt of fatty acid . Calcium stearate
Sol id component rat io . (B) / (A) . 0. 80 (Out of the scope of
the present invention)
So 1 i d component rat i o . (C) / (A) . 0. 4 (Out of the scope of
the present invention)
Weight of coated film (g/cm2) . 15
<Comparative Example 4~
Coating was carried out according to the lubrication
process B (Phosphate layer + Reactive soap).
<Results~
The results of the above described tests are shown in Table
1. As shown in Tab 1 a 1, Embodiment Examp 1 es 1 to 4, where the
aqueous lubricant of one process type of the present invention
was used for high efficient cold forging, can form a coating
layer with excellent performance, and are less number of
treatment steps and less plant area for coating process. And,
it is also understandable that the aqueous lubricant of the
present invention may not produce much industrial waste
products, that is waste drainage and waste sludge. In
Comparat ive Examp 1 a 1, where the rat i o of (B) / (A) i s out of the
scope of the present invention, and in Comparative Example 2,
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17
where the ratio of (C)/(A) is higher than the scope of the
present invention, burning are observed and inferior process
performance are shown. For the coating obtained in Comparative
Examp 1 a 3, where both (B) / (A) and (C) / (A) are s 1 i ght 1y
different from the scope of the present invention, the
dimensional accuracy was insufficient. Further, in Comparative
Example 4, where (phosphate layer + reactive soap) were applied
as same as a conventional process, similar process performance
with that obtainable in the present invention are shown,
however, this Comparative example requires more treatment steps
and requiring more plant area necessary for process, and
furthermore, it produces greater amount of waste products.
Table 1
Performance Simplification Enviroment
(Resistance Number Total plant DrainageSludg
to
burning) / (Dimenof treat area for
sional accuracy)went stepprocess (m')(t) (kg)
EmbodimentGood/0 mm 3 9 0 0
Exempla
1
EmbodimentGood/0 mm 3 9 0 0
Example
2
EmbodimentGood/0 mm 3 9 0 0
Example
3
EmbodimentGood/0 mm 3 9 0 0
Ex amp
1 a 4
ComparativeNo good/-*1 3 9 -*1 -*1
Example
1
ComparativeNo good/-*1 3 9 -*1 -*1
Example
2
ComparativeGood/-0.5 mm 3 9 -*2 -*2
Ex amp
1 e3
ComparativeGood/0 mm 11 90 570 100
Example
4
*1: No data due to inferior process performance.
*2: No data due to occurrence of under fill.
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EMBODIMENT EXAMPLES AND COMPARATIVE EXAMPLES[II]
<Metallic Materials Steel bar of JIS G 4105 SCM420,
Diameter . 50 mm, Length . 140 mm.
<Lubrication process Same as Lubrication Process A (one
process type) as in embodiment example and comparative example
[I] .
<Usual cold forging) Section area reduction rate . 51°/a, Cold
forging mold . High Speed Steel, Cold forging punch . High
Speed Steel.
<High efficient cold forging Section area reduction rate 77%"
Cold forging mold . High Speed Steel, Cold forging punch .
High Speed Steel.
<lubricants
Us i ng t he (A) , (B) and (C) as be 1 ow, and aqueous 1 ub r i c ant
of one process type was prepared by adjust ing (B) / (A) and (C) /
(A) as Table 2 and tested.
Water soluble inorganic salt (A) . Sodium tetraborate
Wax (B) . Polyethylene wax
Metal salt of fatty acid (C) . Calcium stearate.
<Results~
As shown in Table 2, in the usual cold forging of which
section area reduction rate is 51°/g good results are obtained
in all of the lubricant, namely, good resistance to burning as
well as good dimensional accuracy can be obtained even though
the rat i o of (B) / (A) i s 1 ess than 0. 60 or more than 0. 70. On
the other hand, in the high efficient cold forging of which
section area reduction rate of 77°/a good lubricant performance
can be obtained only when the rat io of (B) / (A) is in a narrow
range of 0. 60 to 0. 70. Simi larly, in usual cold forging, good
results are obtained even though the ratio of (C)/(A) is less
than 0. 1 or more than 0.3. However, in the high efficient cold
forging, good results can be obtained only when the ratio of (C)
CA 02419732 2003-02-17
19
/(A) is in a narrow range of 0. 1 to 0. 3.
Table 2
One
process Cold forging Resistance Dimensional
type
lubricant
(B) (C) t o b a r Ac c a r
/ / n i n g acy
(A) (A)
0. 55 0. 2 Usual cold forgin O O
0. 55 0. 2 High eff icient D D
cold forging
0. 65 0. 2 Usual cold forgin O O
0. 65 0. 2 High eff icient O O
cold forging
0. 75 0. 2 Usual cold forgin O O
0. 75 0. 2 High eff icient D O
cold forging
0. 65 0. 05 Usual cold forgin O O
0. 65 0. 05 High eff icient D O
cold forging
0. 65 0. 15 Usual cold forgin O O
0. 65 0. 15 High eff icient O O
cold forging
0. 65 0. 35 Usual cold forgin O O
0. 65 0. 35 High efficient D D
cold forging
ADVANTAGE OF THE INVENTION
As described above, the aqueous lubricant of the present
invention enables to form a coating layer having high
performance to the surface of metallic materials. And less
number of treatment steps and less plant area necessary for
coating process are required in the present invention. In
addition, aqueous lubricant of the present invention produces
less industrial waste and is preferable for global
environmental protection.
Further, the process of the present invention enables to
improve the process by saving the treatment time of coating, by
increasing the efficiency of coating, by saving the energy and
by saving the production cost.
