Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF T~IE lNVENTION:
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This invention relates to a method and an appara-tus
for plastic-working a metallic material, and more particularly
to lubricated plastic-working method and apparatus employing
means for electrically increasing the amount of a lubricant oil
intervening between a working tool and a work to ensure smooth
plastic-working operations.
In a plastic-working operation (e.g., rolling or
drawing) of a metallic material, it is the conventional practice
to employ as a lubricant a non-emulsion type lubricant oil which
is generally called "neat oil" or an emulsion type lubricant
oil which is obtained by adding water to neat oil for a cooling
effect. The degree oE lubricating effect is judged by whether
a su'ficient quantity of lubricant oil intervenes between a
work ænd a tool such as a working roll or drawing die. The
most important factor which dictates the intervention of a
lubricant oil is the adherence of the lubricant oil to the
working tool and the work. There have thus far been made var-
ious attempts to improve the adherence of the lubricant oil,
for example, by chemically modifying the property of the lubri-
cant or by varying the particle size o~ the emulsion, but none
of them turned out to be satisfactory. Especially, known
emulsion type lubricant oils are in most cases of oil-in-water
type so that they are inferior to neat oil in adherence to the
work. Whereas satisfactory lubrication cannot be expected
from stable lubricant emulsions with a small oil concentration
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which are poor in adherence by nature. Tnis difficulty is
usually coped with by using an emulsion o_ a relative large
particle size which is however unstable and incapable of
effecting uniform and stable lubrication. In addition, it has
been difficult to control the adherenoe of lubricant oil to an
extent optimum for particular working conditions since it
varies over a wide range depending upon the kind of the lubri-
can~ oil and the working conditions.
SU~L~RY OF THE INVENTION:
With the foregoing in view, the present invention has
as its object the provision of a method and an apparatus for
increasing the adherence of a lubricant oil to a work and/or a
working tool in a lubricated plas~ic-working of a metallic
mater-al.
It is a more particular object of the present inven-
tion to provide a method and an apparatus for electrically
controlling the adhorence of a lubricant oil to a work and/or
a working tool in a lubricated plastic-working of a me~allic
material depending upon the operating conditions or the nature
of the work.
According to the present invention, there is provided
a method for electrically increasing the degree o~ lubrication
in a lubricated plastic-working of a metallic material, com-
prising: incorporating a working tool and/or a work into a
DC circuit to form a pole in face-to-face relation with an
opposite pole; and conducting current between the two opposing
poles to produce an electric field in an emulsion type lubricant
oil prevailing the~ebetween, causing the lubricant oil to be
electrically pulled toward the working tool and/or the work;
thereby increasinc3 the adherence of the lubricant oil to the
working tool and/or the work.
The present invention also provides an apparatus
for carrying out the method mentioned above, which comprises:
a lubricant oil trough member holding an emulsion type lubri-
cant oil in contact with a working tool and/or a work; and
a DC circuit incorporating the working tool and/or the work
to orm a pole tA~ and having an opposite pole (B) disposed
in contact with the lubricant oil and in ~ace-to-face relation
with the pole (A) to produce an electric field in the
lubricant oil upon conducting a current between the two
pole~3 (A) and (B); thereby causing the lubricant oil to he
electrically pulled toward the working tool and/or the work
to increase the adherence of the lubricant oil to the working
tool an~/or the work.
Tlle above and other objects, features and advantages
of the invention Will be apparent from the ollowing
descriptionand the appended claims, taken in con~unction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS:
Fig. 1 is a graph showing experimental data;
Fig. 2 is a schematic diagram of lubricated rolliny
according to the present invention;
Figs. 3, 4 and 5 are graphs showing experimental
data;
Fig. 6 is a schematic diagram showing different
forms of lubricated drawings according to the invention;
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Figs. 7 and 8 are graphs showing experimental
data;
Fig.9 is a schematic diagram showing different
forms of lubricated drawing according to the invention;
Fig. 10 is a schematic diagram of lubricated
rolling with divided control of lubrication according to
the invention;
Fig. 11 is a graphic illustration of the pattern
of the divided lubrication control attained bythe method
of Fig. 10; and
Figs. 12 to 14 are graphic illustra-tions similar
to Fig. 11 but showing patterns of more finely divided
lubrication control attainable by the method of the invention.
P~RTICULAR DESCRIPTION OF THE INVENTION:
In a preliminary experiment conducted by the
present inventors, a steel plate and a copper plate are
immersed in a lubricant oil bath holding an anion type emulsion
lubri.cant (using triethanolamine oleate and having an
emulsion concentration of 10% and an average~particle si~e
of 5 microns) and a diversity of voltages were applied
across the steel and copper plates serving as positive
and negative poles, respectively. The amounts of adhered
lubricant oil resulting from the application of voltages
are shown in the graph of Fi~. 1 in relation with time
of immersion. As clear therefrom, the adherence of lubricant
oil to the steel plate is increased with both the voltage
and the time of immersion. For example, at an immersion
time of 10 seconds, the adherence of the lubricant oil under
conduc~ing condition at 50~ is about 10 times greater than that
or non-conducting condition. This increase in adherence is
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considered to be attributable to the attraction of negatively
charged anion type emulsion on the posi-tive pole formed by the
steel plate.
The adherence of a cation type emulsion lubricant can
also be increased by applying a voltage across a cathodic steel
plate and an anodic copper plate.
In a similar experiment using a nonion type emulsion
lubricant oil and a non-emulsion type lubrican~ oil, the it
has been confirmed that the adherence does not increase in any
appreciable degree at low voltages but remarkably increases
when a relatively high voltage is applied for a long time per-
iod. For example, the adherence amounted to about 8 g/m2 by
applicatlon of 100V for 8 minutes, which is four times as great
as ~h2 adherence under non-conducting condition ~about 2 g/m2);
It is sathered from the results of the experiments that the
applica"ion of voltage causes electrolytic dissociation to
ionizable groups or substances like R-COOH which are usually
contained in lubricant oils, as follows
2R-COOH + 2e ~ 2R-COO + H2 ~
pulling R-COO thus produced toward the anodic steel plate.
I. Lubricated Rolling
The method of the invention was experimentally applied
to lubricated rolling operation using an appara~us as shown in
Fig. 2, in which indicated at 14 a steel strip, at 15 and 16
are working rollsf at 17 and 18 are lubricant oil feed nozzles,
and at 19 and 20 are lubricant oil pools. Pole plates 21 and
-- 6
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22 ~re immersed in the lubricant oil pools 19 and 20 opposingly
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in face-to-face relation wi-th the working rolls.~7 and 1~,
respectively. The roll 15 and pole plate 21 are ~onnected to
a DC power source 23, while the roll 16 and pole plate 22 are
connected to another DC power source 24.
In the rolling operation, for assessing the adherence
of the lubricant oil to the working rolls at different voltages,
the æ~ounts of lubricant oil adhered in a short time period of
contact between the lubricant oil and the rolls were measured
in consideration of the speed of the working rolls~ The lubri-
cant oil used in the rolling op~ration was an anion type emul-
sion (emulsified by triethanolamine oleate and having a concen-
tration of 10 ~ and an average particle size of 0.9 microns).
As a result, it has been confirmed that the amount of adherence
has a tendency of increasing with the applied voltage even in
a short contacting time as shown in Fig. 3. Fig. 4 shows the
amounts of adherence of the same lubricant oil measured upon
a lapse of 0.5 seconds after application of currents of various
densities. It is clear therefrom that the adherence of the
lubricant oil increases with the current density.
According to the present invention, the adherence o~
the lubricant oil on the working rolls is amplified to a con-
siderable degree by applying a current across the lubricant oil
between the working rolls and electrode plates, and the amount
of adherence can be controlled as desired simply by adjusting
the applying voltage or current to ensure smooth rolling
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operation. The adherence of the lubricant oil has a great
influence on the load for the rolling operation. In this
connection, the effects of applied voltages on thè rolling
load (rolling lubrication) -~ere tested by a rolling operation
according to Fig. 2 and under the following conditions.
Rolling ~onditions: -
.
Rolling material: Al having dimensions of
1.5 mmt x 50 mmW (coil)
Rolling temperature: 360C (at entrance)
Rolling reduction: 60 ~
RoLling speed: 25.7 m/min.
Roll diameter: 155 mm
Lubricant oil: 3 % emulsion of aluminum hot
rolling oil
Size of pole plate:20 mmh x 65 mm~
As clear from Fig. 5 which shows the results of the
rolling test, the rolling load which is as high as about 11
tons in an ordinary lu~ricated rolling operation under non-
conducting condition (at zero volt) is markedly reduced to
about 9 tons at 20 V and to less than 6 tons at 50 V due to
the effects of the present invention. In ~ig. 5, the last
half portion of O-volt curve plots the experimental data
resulting from application of 50 volts which was initiated at
the arrowed point. The voltage applied half-way of the roll-
ing operation has a certain degree of load reducing effect
which however is lower than that which would be obtained by
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applying the same voltaye from the start.
In the embodiment of Fig. 2, the lubricant oil pools
are provided at one sides of the working rolls and elec-tric
current is conducted across the working rolls and immersed
pole plate5. In this connection, it is also possible to use
the nozzles 17 and 18 as a neyative pole, continllously spouting
the lu~ricant oil toward the surfaces of the wor~ing rolls
forming a positive pole. In such a case, it is preferred to
employ nozzles which have an increased width along the length
of the working rolls. It is also possible to use the rolling
strip as a positive pole, locating the electrode plate~
(nega~ive poles) vis-a-vis with the upper and lower sides of
the entering rolling strip and filling the lubricant oil in th,e
spaces between the rolling strip and the respective negative
1~ electrode plates.
II. Lubricated Drawing:
The method of the present invention is also applicable
to lubricated drawins by using an apparatus as shown in Fig. 6,
in which indicated at 1 is a wire red being drawn, at 2 a die,
at 3 a die holder, at 4 a cylindrical member internally defining
a lubricant oil chamber 4a, at 5 an insulating joint member
joining the die holder 3 and the cylindrical member 4 together,
at 6 an insulating wire guide member, at 7a a lubricant oil
inlet, at 7b a lubricant oil outlet, and at 8 a compressed
air blow in hole (for preventing leakage of the lubricant oil
through the gap space between the wire guide member 6 and the
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wire 1). The die holder 3 and cylindrical member 4 are connected
to a DC power source 9. In this embodiment, electric current is
conducted between the die holder 3 and the cylindrical member
4, form ng the positive and negative poles by the drawn wire 1
and the inner peripheral surface of the cylindrical member 4,
respectively, while circulating a lubricant oil through the
lubricant oil chamber 4a.
An aluminum alloy wire rod of 3.2 mm~ x 120 mm was
drawn by an apparatus as shown in Fig. 6, using an anion type
emulsion lubricant oil (concentration: 10 %) and applying a
varying voltage of 0 to 50 volts. The adherence of the lubri-
cant oil to the wire in a contacting time period of 5 or 10
seconds was measured. The results are shown in Fig. 7.
As clear from Fig. 7, the adhered lubricant oil has an
averag2 film thickness of less than 5 ~m at zero volt but it
increases sharply with the applied voltage, to 54 ~m at 50
volts x 5 seconds of contacting time and to as great as 70 m
at 50 volts x 10 seconds of contacting time. m us, the adheren-
ce o~ the lubricant oil to the wire is drastically increased by
conducting electric current between the wire and the inner
peripheral wall of the cylindrical member in a manner to
produce a potential difference between the wire and the lubrl-
cant oil, It will also be seen from Fig. 7 that the adherence
increases with the voltage and the time of contact between the
wire and the lubricant oil. Therefore, the adherence of the
lubricant o~l can be controlled to a value optimum for a
-- 10 --
particular drawing condi-tion by adjusting the voltage ~f the
DC power source 9 (Fig. 6), thereby to ensure very smooth draw-
ing operation. The adherence of the lubricant oil is also
closely related with the load required for the drawing opera-
tion and the rate of wire seizure. The effects of reducing-
~he dra~ln, load (incre~ir~ l~ik_ic~t~ A d~..ir.g` ~
rate of wire seizure by the application of voltage were tested
under the following conditions.
Drawing Conditions:
Lubricated drawing machine:
Length of lubricant chamber 4a: 100 mm
Inner dia~ter of lubricant chamber 4a: 13.2 mm
Diameter of die: 2.9 mm
Lubricant oil: Anion type 10 % or 3 % emulsion of
neat oil .
Wire rod: Aluminum alloy of 3.2 mm in diameter
Drawing reduction: 18 %
Drawing speed: 1-10 m/min.
Voltage: o - A O V
Rod draw~ Drawbench
(1) Effect of reducin~ drawing load
The application of voltage manifested a distinctive
effect of reducing the drawing load by 6-25 % as shown in
Fig. 8, the effect being greater with an anion t~pe emulsion
having an about 10 ~ oil concentration.
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(2) Effect of lbssening rod seizure:
Rod seizure occurred in non-conducting drawing opera-
tions both at a drawing speed of 6 m/min with a 10 % emulsion
and a drawing speed oE 3 m/min with a 3 % emulsion. Upon
applying a voltage of 40 volts, the drawing operations under
the same conditions proceeded smoothly without rod seizures.
As clear from these test results, the lubricating
method of the present invention also contributes to reduce-the
drawing load while precluding the rod seizures.
The method of the invention is explained by way of
lubrica ed drawing of a wire rod in the embodiment of Fig. 6
but it can also be applied in a similar manner to pipe drawing
as show;l in Fig. 9, in which indicated at 1' is a pipe being
dra~-n, at 2 a die, at 4 a cylindrical member, at 10 a conduc-
tive press roller for applying current to the pipe 1', and
at 11 a plug which controls the inside diameter of the drawn
pipe. me plug 11 is supported by a rod 12 in a fixed concen-
trical position with~" the die 2. The cylinder 4 is provided
with a lubricant oll inlet 7a for supplying a lubricant oil
around the outer periphery of the pipe 1' while the support
rod 12 is internally provided with a lubricant oil supply
passage 13 for supplying the lubricant oil around the inner
periphery of the pipe 1'. m e cylindrical member 4 and press
roller 10 are connected to a DC power source 9 for conducting
durrent during the drawing operation between a negative pole
formed on the inner periphery of the cylinder 4 and the outer
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periphery of the support rod 12 and a positiYe pole formed on
the inner and outer peripheries of the pipe 1'. In this
embodiment, the lubricant oil of anion type emulsion is affec-
tively adhered on the inner and outer peripheries of the pipe 1'
forming a positive pole to ensure smooth drawing operation free
of pipe seizures.
III. Divided Control of Lubrication:
Referring now to ~ig. 10, there is shown a rolling
mill for controlling the shape of a rolling strip utilizing
the c~ilductive lubrication of the present invention. In this
embodiment, working rolls 7a and 7b are directly contacted
with a lubricant oil 2 in troughs 8a and 8b which are located
along the lengths of the respective rolls 7a and 7b, so that
the lubricant oil 2 is fed in the rolling direction'as the
working rolls 7a and 7b are rotated. Located within the
lubricant oil troughs 8a and 8b are a number of pole plates
9a-1 to 9a-3 and 9b-1 to 9b-3 which are positioned in face-
to-face relation with the'working rolls which form an opposite
pole of an electric circuit for producing an electric field in
the lubricant oil 2 between the opposing poles. In this
particular embodiment, the pole plates 9a-1', 9b-1, 9a-3 and
9b-3 which face the opposite end portions of the working rolls
are connected to a common power source llb through a voltage
regulator lOb, separately from the intermediate pole plates
9a-2 and 9b-2 which are connected to another power source la
through a voltage regulatorlOa, to control the lubrication
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independently in the middle and opposite end portions of the
working rolls 7a and 8b. A number of detectors 12-1 to
12 3 are located across the width of the rolled strip A to
detec-t its shape and dimensions, the opposite end detectors
12-1 and 12-3 being connected to the voltage regulator 10b
while the middle detector 12-2 being connected to the
voltage regulator 10a.
~pon commencing the rolling operation, a voltage is
applied between the respective opposing poles to pull the
lubricant oil electrically toward the working rolls thereby
to ad~ust the adherence o~ the lubricant oil on the working
rolls. EVel~ if the adherence is uniformly controlled along
the len~ths of the working rolls, there sometimes occur
variations in the degree of lubrication which cause elongations
in the middle portion of the rolling strip or undulations
along the opposite longitudinal sides of the strip A.
These conditions are immediately detected by the detectors
12-1 to 12-3 and the voltage regulators 10a and 10b are
operated to ad~ust counteractively the voltages.to be applied
to the respective pole plates. More particularly, in a case
where the lubrication in the opposite end portions of the
rolling strip is deficient, the voltage to the pole plates
9a-1, 9b-1, 9a-3 and 9b-3 is increasedto increase the
adherence of the lubricant oil to the opposite end portions
of the working rolls. On the other hand, when the lubrication
in the middle portlon o~ the rolling strip is deficient,
the voltage to the pole plates 9a-2 and 9b-2 is
boosted to increase the adherence of the lubricant
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oil to the middle portions of the working rolls. By so doing,
uniform lubrication is maintained along the length of the work-
ing rolls to allow produc-tion of rolled plates of high quality
which are free of elongations in the middle portion or
undulations along the longitudinal edges thereof.
The separate control of the adherence of the
lubricant oil in the middle and opposite end portions of the
working roll can be expressed by a control pattern of Fig. 11.
In a case where more than 5 sets of a pole plate and a
~0 detec~:or, each connected to a power source and a voltage
regulator of a separate control circuit, are juxtaposed in
the transverse direction, it becomes possible to control
the adherence of the lubricant oil in a more finely divided
pattern as shown in Flgs. 12 to 1~. The pole plates are
located within the lubricant oil troughs 8a and 8b in the
embodiment of Fig . 10 . However, they may be omitted by
using the upright wall portions of the troughs 8a and 8b
which are disposed via-a-vis with the respective working
rolls.
Further, the terminal end of each electric control
circuit which is directly connected to the working roll in the
embodiment of Fig. 10 may be connected to a conductive slide
member which is positioned in contact with a working roll
slidably relative to the rotation of the working roll, thereby
to prevent current leakage to a roll bearing or chock.
Such conductive slide member is preferred to be formed of
graphite or a material which is highly conductive and .
resistant to abrasive wear.
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It will be appreciated from the foregoing description
that the lubricating me-thod of the present invention has a high
practical value particularly in lu;~ricated drawing or lubricated
rolling operations. To summarize the erfects accruing from the
method of the present invention:
~ a) The adherence is increased irrespective of the kind
of the lubricant oil (anion-, cation- or nonion type), and with
a lubrica~t oil of anion type emulslon the adherence can be
dras~ically increased by application of a relatively small
voltage.
(b) The adherence of lubricant oil to a working tool
(e.g., a die or roll) can be controlled by ad~usting the apply-
ing voltage or current, providing optimum lubrication with use,
of a llibricant oil of a given concentration depending upon the
nature or the work and conditions of a drawing or rolling
operation.
(c) Even if the lubricant oil undergoes a change during
plastic-working operation (e.g., a change in particlè size or
concentration of the emulsion), it is possible to control the
adh~rence counteractively, constantly permitting the plastic-
working operation to proceed stably.
~ d) Seizure OL a work is suppressed to a minimum,
coupled with other advantageous eEfects such as prolongation of
the service life of dies and working rollsr lenssened drawing
or rolling loads, higher quality of drawn or rolled products.
While particular preferred embodiments have been
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described, i-t is -to be understood that the invention is not
limited by -the particular details shoT~n and various modifica-
tions and alterations can be made without departing from the
scope of the inven~ion as defined by the appended claims.
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