Description
Method and device for lubricating the cylinders of a roll
stand
Technical field
1
The invention relates to a method and a device for lubricating
the cylinders of a roll stand, in particular for roll nip
lubrication in a roll stand for a roll band, wherein a
mixture made out of water and oil is produced by means of a
mixing and spraying device, which is supplied with water by
means of a first supply line and is supplied with oil by
means of a second supply line and said mixture is sprayed
onto the strip and/or into the roll nip and/or onto at least
I one of the cylinders of the roll stand.
Prior art
It is known that for the production of rolling stock its
surface quality can be improved if the friction coefficient
between the cylinders and the rolling stock is reducr-,d. By
introducing a lubricant during the production of a roll band
for example, not only 1s the energy to be expended for the
rolling process reduced, but the service life of the cylinders
of a roll stand is also increased. Usually oil and water are
mixed into an emulsion in a mixer. By means of connecting
lines, which may be one or more meters in length, this
emulsion is supplied to an arrangement of nozzles which spray
the emulsion onto the strip and/or into the roll nip and/or
onto the cylinders.
Af rtain operating time, how f th
roll nip lubrication decreases as saponification occurs both
in the mixing unit and in the nozzles and also in the
connecting lines, the deposit of which reduces the active
flow area. If a saponification particle detaches itself from
the internal wall of a pipe or of the mixer and is washed
into the outlets of a nozzle, this may become blocked. In
this area the roll nip lubrication then fails completely.
To solve the problem of saponification and the associated
reduction in the effect of the lubrication, maintenance work
for the roll nip lubrication is necessary. In such
maintenance, the mixer, the pipes between the mixer and
nozzle, and the nozzles themselves are flushed with hot water,
if necessary with the addition of one or more chemical
cleaning agents, or blasted to clear them.
Such roll nip lubrication is known, for example, from EP 2 040
860 B 1. Hot water is added to the oil or water supply line,
or to the mixing unit itself, by means of a third supply
line. During maintenance of roll nip lubrication, the rolling
process is interrupted. The heated water is kept ready in a
thermally insuldLrd hot water tank. The provision oi the hot
water, as well as the supply by means of a third thermally
insulated line, is associated with corresponding technical
effort.
Representation of the invention
It is an object of the present invention to specify a method
and a device for lubricating the cylinders of a roll stand
which is constructed as simply as possible and the
maintenance of which affects the availability of a rolling
mil tle as possible.
This object is achieved for a method with the features of
claim 1 and for a device with the features of claim 11.
According to a fundamental idea of the invention, the hot
water used for cleaning purposes is produced by a heating
device, by means of which the water flowing into the water
supply line is heated virtually in line. This heating device
is permanently installed and only active for a time interval
which is predetermined by a control device. As a result, a
third supply line which supplies hot water to the mixing unit
or to connecting lines between the mixing unit and nozzle is
unnecessary. The constant provision of hot water is likewise
unnecessary. The expense of a thermally insulated container
J
:I for the provision of warm or hot water is spared as a result.
This has several advantages. On the one hand, a system for
roll nip lubrication can be easily constructed. On the other
hand, cleaning of the roll nip lubrication can be performed
more easily. During a short maintenance downtime the hot
water for flushing the mixing unit and nozzles is also
available very quickly and its temperature can be adjusted to
requirements very easily. This also enables cleaning during
short production downtimes so that saponification can be
countered at an early stage. Energy can be supplied to the
heating device in various ways, for example electrically or
using another fuel, e.g. gas or oil.
In a preferred embodiment, the heating device can be operated
electrically, e.g. be designed as an instantaneous water
heater. An instantaneous water heater has several advantages.
On the one hand, the necessary construction volume for a
rolllng mill compared with a hot water cyllnder is much
smaller. The water temperature necessary for cleaning can be
very precisely predetermined and adjusted by means of
electronic control of the energy supply to the individual
resistance heating elements. As a result, the energy
requirements can be adjusted to the level of contamination.
It may be favorable if the control unit for determining the
time interval in which cleaning takes place uses a process
variable from cylinder lubrication, for example a measurement
signal in the water supply, which indicates the level of
contamination of the mixing and spraying device. Such a
measurement signal. may, for example, be obtained by means of
a sensor which is arranged in the water supply. The sensor
may be a pressure sensor or a flow sensor.
For efficient cleaning, it may be advantageous if the control
unit controls the heating device in such a way that the water
flowing to the mixing and spraying device is heated to a
predetermined temperature of more than 60°C and is adjusted to
this temperature.
Saponification of the emulsion can be reduced by means of a
permanent water treatment plant installed in the watcr
supply, e.g. an ion exchanger or osmosis plant. In addition,
soft water is favorable for an instantaneous electric water
heater as there is less calcification on the heating
elements.
In a particularly preferred embodiment provision can be
made for the mixing and spraying device to be composed of a
number of nozzle-mixer-units, whereln each nozzle-m~xerunit
is supplied with both water and oil separately. In
contrast to the prior art, where a mixlng devlce supplles
sever?l nozzles, in the present embodiment of the
invention a separate mixing unit is assigned to each
nozzle. The design of each nozzle-mixer-unit is
structurally compact as a unit and includes both the
mixing function and the spraying function. As a result
there are virtually no connecting lines between the mixer
and the nozzle in which saponification could occur. The
dwell time of the emulsion/dispersion in the unit is very
short, resulting in reduced saponification. As a result,
the rolling process need not be interrupted as often for
the purposes of cleaning the roll nip lubrication.
Maintenance work can be made easier ~f each of these nozzlemixer-
units can be released from its fixture device by means
of a quick release fastener e.g. a bayonet fastening. By this
means contaminated units can be changed very quickly during
maintenance downtime.
Brief description of the diagrams
For further explanation of the invention, in the following
section of the description reference will be made to drawings
from which additional advantageous embodiments, details and
developments of the invention based on a non-restrictive
exemplary embodiment can be taken. These drawings show:
Figure 1 a block diagram of a roll nip
lubricationdesigned according to the
invention;
Figure 2 a nozzle-mixer-unit which is fastened in a
fixture device by means of a quick release
fastener.
Embodiment of the invention
Figure 1 shows a diagrammatic view of an exemplary embodiment
of the device according to the invention for lubricating the
cylinders of a roll stand. For the sake of clarity, only the
two cylinders 12 of the roll stand are shown, in the roll nip
j of which the roll band 8 is rolled. On the inlet side of the
cylinders 12, a mixing and spraying device 10 can be seen.
$
This mixing and spraying device 10 is composed of a number of
nozzle-mixer-units 1, each of which is supplied with oil and
water. On the one hand, each of these nozzle-mixer-units 1
operates as a mixer which processes oil and water to form a
homogenous emulsion/dispersion. On the other hand, each of
these nozzle-mixer-units 1 operates as a spraying unit which
:j introduces the emulsion into the roll nip in the form of a
spray. This introduction can take place by means of spraying
in the direction of the roll gap, or in the direction of the
i cylinders and/or in the direction of the facing surface of the
1 roll band. The dispersion is a water-oil mixture, composed of
extremely small oil droplets in water.
In the exemplary arrangement of Figure 1, three noz7le-mixerunits
1 can be seen on the upper side of the roll band 8 and
three on the underside of the roll band 8. The upper
arrangement of the nozzle-mixer-units 1 is supplied by an
upper supply branch 4, the lower by a lower supply branch 5,
each supplied with both oil and water. For this purpose,
supply branches 4, 5 are fed with water by a first supply
line 3 and with oil by a second supply line 2.
A heating device 6 is permanently installed in the first
supply line 3 (water supply), by means of which the water
flo m a source not identifie th
mixing and spraying device 10 can be heated for the purposes
of cleaning. This heating device 6 is designed as an
instantaneous water heater which has several heating elements
designed as electric resistance heating. The method of
construction and installation of an instantaneous water heater
can be assumed to be known and do not need to be explained in
more detail here. As indicated by the dashed line in Figure
1, the energy supply to the heating elements of the
instantaneous water heater is controlled electronically by
means of a microcomputer.
The second supply line 2 (supply) supplies the mixing and
spraying device 10 with oil. It is likewise split into an
upper supply branch 4 and a lower supply branch 5. A
respective dosing pump 7 is connected in each of these
branches 4, 5. Each of these dosing pumps 7 is controlled by
the control unit 9 in such a way that the amount of the oil
feed can be predetermined separately in the upper branch 4
and in the lower branch 5.
As aforementioned, the mixing and spraying device 10 consists
of several nozzle-mixer-units 1. These nozzle-mixer-units 1
are each designed as a structural unit. In other words, seen
in the direction of flow, the mixer and spraying unit are
locally arranged with one directly behind the other. By mixing
oil and water in an integrated structural unit, the dwell
time for the emulsion/dispersion in this structural unit is
very short. The cleaning process is comparatively simple as
less saponification takes place.
The time at which a cleaning phase starts, as well as the
duration of a rinsing procedure, is predetermined by the
con it 9. The control unit 9 the
measurement signal of a sensor 13 in the water supply line 3
for this purpose. The measurement signal supplied by the
sensor 13 reflects the level of contamination of the mixing
and spraying device 10. In the present example, the sensor 13
is a pressure sensor. Figure 1 shows this pressure sensor 13
downstream of the instantaneous water heater 6. Likewise,
1 such a pressure sensor could also be arranged in the upper
I branch 4 or in the lower branch 5 of the water supply.
During the cleaning phase, the instantaneous water heater 6
heats the circulating water to a temperature of more than 60"
Celsius. In a manner known per se, the energy supply to the
heating elements of the instantaneous water heater 6 is
I predetermined in such a way that a predetermined water
1 temperature can be maintained.
During a cleaning phase the dosing pumps 7 are inactive,
resulting in the oil supply to the nozzle-mixer-units 1 being
interrupted. The hot water flowing to the individual nozzlemixer-
units 1 cleans these and removes any existing
saponification and deposition. The hot water necessary for
cleaning is generated virtually online in the water supply
line and does not originate from a reservoir.
In Figure 1 a water treatment plant 11 is installed upstream
of the instantaneous water heater 6. This water treatment
plant 11 is an ion exchanger which removes lime and salts
from the water and thus softens the water, as a result of
which the heating elements of the Instantaneous water heater
6 are less prone to calc~fication.
In contrast to the prior art, where a mixer supplies a number
of spray nozzles and the distance bet d the
spray nozzles usually involves a length of pipe of more than
one meter, the dwell time of the emulsion in the device
according to the invention is far shorter. The extent of
saponification is less with the mixing procedure and the
spraying procedure taking place in one structural unit. If i deposits are formed in the mixer or nozzle nevertheless,
these can be removed with greater ease and the surface on
which deposits may form is comparatively small as a result of
the integrated construction. This leads to shorter
maintenance intervals and consequently enables the
availability of a rolling mill to be increased.
In a schematic diagram Figure 2 shows the possible
fastening of a nozzle-mixer-unit 1 by means of a snap-lock
connection, e.g. a bayonet fastening 15 in a fixture device
14. During maintenance downtime, a nozzle-mixer-unit 1 can
be released from the fixture device 14 very quickly by
I
I means of such a quick release fastener. The contaminated 1
unit 1 can then be cleaned or maintained.
A major advantage of the device according to the invention is
firstly the simpler opportunity for cleaning which is possible
without chemical cleaning agents and acids, obviating the need
for cleaning agents and acids as consumables.
Although the invention was illustrated and described in
greater detall by the preferred exemplary embodiment, the
invention is not restricted by the disclosed examples and the
person skilled In the art can der~ve other versions therefrom
without departing from the scope of protection of the
invention. Thus, it is conce~vable that instead of the
aforementioned individual instantaneous water heater, a
number of jnstantaneous water heaters further
conceivable that each nozzle-mixer-unit is assigned its own
instantaneous water heater with a lower connected load.
Composition of the reference characters used
1 Mixer-nozzle-unit
2 Supply line for oil
3 Supply line for water
4 Upper supply branch
5 Lower supply branch
6 Inline heating device
7 Dosing pump for oil
8 Roll band
9 Control device
10 Mixing and spraying device
11 Water treatment plant
12 Cylinder
i 1 13 Sensors
:I
14 Fixture device
15 Snap-lock connection
Claims
1. A method for lubricating the cylinders of a roll stand, in
particular for roll nip lubrication in a roll stand for a
roll band, wherein a mixture made out of water and oil is
produced by means of a mixing and spraying device, which is
supplied with water by means of a first supply line (3) and
is supplied with oil by means of a second supply line (2) and
said mixture is sprayed onto the strip and/or into the roll
nip and/or onto at least one of the cylinders of the roll
stand, characterized by the method step that the water
flowing to the mixing and spraying device (10) is heated for
a period of time predetermined by a control unit (9) by means
of a heating device (6) provided in the first supply line
(3).
2. The method as claimed in claim 1, characterized in that
the hot water flows through the mixer and/or nozzle of the
roll nip lubrication device.
3. The method as claimed in claim 1, characterized in that
an electric instantaneous water heater is used as a heating
device (6), the energy consumption of which is controlled by
the control unit (9) .
4. The method as claimed in claim 2, characterized in that
a sensor (13) is arranged in the first supply line to record
the flow and/or the pressure and/or the temperature, the
measurement signal of which is supplied to the control unit
(9) and is used by the control unit (9) for the control of
the heating device (6).
5. The method as claimed in claim 3, characterized in that
the control unit (9) controls the heating device (6) in such
a way that water flowing to the mixing and spraying device
(10) is heated to a predeterminable temperature value of more
than 60°C and is adjusted to this value.
6. The method as claimed in one of the claims 1 to 4,
characterized in that the water flowing to the mixing and
spraying device (10) is prepared by means of a water
treatment plant (11) arranged upstream of the heating device
(6).
7. The method as claimed in claim 5, characterized in that
softening of the water and/or a removal of undesired salts
from the water is performed in the water treatment plant
(11).
8. The method as claimed in one of the claims 1 to 6,
characterized in that the mixing and spraying device (10) is
formed by an arrangement of nozzle-mixer-units (I), wherein
water and oil is supplied to each nozzle-mixer-unit (1).
9. The method as claimed in claim 7, characterized in that a
number of nozzle-mixer-units (1) in the vicinity of the roll
nip are each arranged on the upper side and the underside of
the rolling stock (8) on the inlet side to the roll nip.
10. The method as claimed in claim 9, characterized in that in
each case the supply of oil is separately predetermined for
the nozzle-mixer-units (1) on the upper side and on the
underside of the roll band (8) by means of a dosing pump (7).
11. A device for lubricating the cylinders of a roll stand, in
for roll nip lubrication i r a
roll band, wherein a mixing and spraying device (10) which is
supplied with water by means of a first supply line (3) and
is supplied with oil by means of a second supply line (2)
produces a mixture of water and oil and sprays this mixture
into the roll nip and/or onto at least one of the cylinders
(12) of the roll stand, characterized in that a heating
device (6) is arranged in the first supply line (3), by means
of which the water flowing to the mixing and spraying device
(10) can be heated for a predetermined period of time by
means of a control unit (9).
12. The device as claimed in claim 11, characterized in that
the heating devj.ce (6) is designed as an electric, oil or
gas-powered instantaneous water heater, the energy consumption
of which can be controlled by a control unit (9).
13. The device as claimed in claim 11, characterized in that a
sensor (13) is arranged in the first supply line (3), the
measurement signal of which is supplied to the control unit.
14. The device as claimed in claim 13, characterized in that
the sensor (13) is a pressure sensor or a flow sensor and/or
a temperature sensor.
15. The device as claimed in claim 12 or 13 or 14,
characterized in that the control unit (9) controls the
heating device (6) in such a way that the water flowing to the
mixing and spraying device (10) is heated to a predefinable
temperature value of more than 60°C and is adjusted to this
value.
16. The device as claimed in one of the claims 12 to 15,
cha ed in that a water treatme
arranged upstream of the heating device ( 6 ) , by means of . .
which the degree of hardness or the salt content of the
water flowing to the mixing and spraying device (10) can be
!!
changed.
17. The device as claimed in one of the claims 11 to 16,
characterized in that the mixing and spraying device (10)
I is formed of an arrangement of nozzle-mixer-units (I),
whereln oil and water is supplied to each nozzle-mixer unit
(1) respectively.
18. The device as claimed in claim 17, characterized in that
each nozzle-mlxer-unit (1) is designed as a structural unit.
1 9 . The device as claimed in claim 17 or 18, characterized in
that a number of nozzle-mixes-units (1) in the vicinity of
the roll nip are each arranged on the upper side and the
underside of the rolling stock (8).
20. The device as claimed in claim 17 or 18, characterized
in that each nozzle-mixer-unit (1) is held in a fixture
device (14) by mean:: of a snap-lock connection (15).
Dated this 10/07/2014
[RANJNA MEHTA-DUTT]
OF REMFRY & §AGAR
ATTORNEY FOR THE APPLICANT[§]
Abstract:
The invention relates to a method for lubricating the cylinders of a roll stand, in particular for
roll nip lubrication in a roll stand for a roll hand. A mixture made out of water and oil is
produced by means of a mixing and spraying device, which is supplied with water by means
of a first supply line (3) and is supplied with oil by means of a second supply line (2) and said
mixture is sprayed to the strip and/or into the roll nip and/or to at least one of the cylinders of
the roll stand. The water flowing to the mixing and spraying device (10) is heated for a
predetermined period of time by means of a control unit (9) by means of a heating device (6)
provided in the first supply line (3).