Note: Descriptions are shown in the official language in which they were submitted.
~ 7~3~ LP 1337
The invention relates to a process and an app~ratus
fcr the deoxidation of hollow bodies such as shells, hollow
blocks or pipes.
I-t is known to deoxidize metal surfaces and especially
steel surfaces prior to transformation. One method of
deoxidizing involves surface treatment with acids, acid
mixtures, alkalines or salt mixtures. For example, in
the case of the processing of shells made of iron
and especially of steel, such as, hollow blocks or pipes
and especially of shells for seamless pipes in
installations such as push-bench plants, Assel mills, plug
mills, hot pilger mills, continuous mills, multiple pipe
mills, up-setters, etc., the inside of the shell, the
hollow block or the pipe must be deoxidized prior *o
introduction of the mandrel bar at a temperature in the
range oE the rolling tempera~ure, that is, around 1000
to 1300C. As a result of the complexity of the
operation in rolling mills of the type mentioned, it has
not been possible hitherto to achieve a complete
deoxidation in an economic manner. Sometimes only such
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short time intervals as about one second are available
for the application of the deoxidizinq aqent.
The proposal had already been made to descale
shells by introducing descaling agents, with the help of
a compressed gas, in a circular motion at one end of the
shell into the inside of the shell, which has been
heated to rolling temperature, and to remove the
residual mixture at the other end of the shell by
suction~ Such process has the disadvantage of requiring
great quantities of gas and descaling agents. For
economic reasons, one must use air as the gas. But, as
a rule, the air acts oxidatively, especially when used
in such large quantities, and also seriously tends to
cool the inside of the shell. Furthermore, the removal
by suction and filtering of the residual mixture of gas
and salts is not without problems.
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An object of the invention is to provide an
apparatus and a process which allows, in the course of
the operation o a rolling mill, the continuous
conducting of a deoxidation process as completely as
possible. Another object of the invention is to efect
the above object with a minimal amount of equipment with
an adapted quantity of deoxidation agent.
The invention provides a process for the processing
of deoxida-tion agents, especially Eor tha deoxidation of
shells heated to rolling temperature for the production
of pipes. The deoxidation agent is fed by volumetric
or gravimetric dosing into a pressure container. From
5 up to 100 g of deoxidation agent is present per square
meter (m2) of the inside wall surface of -the shell. Com-
pressed gas is fed into the pressure container so that a
ratio of from 50 to 750 standard liters of gas per kilogram
of deoxidation agent is attained. The gas and the deoxida-
tion agent are guided as a homogenous mixture through a
transport line to a delivery arrangement, which guides the
homogenous mixture in a circular, turbulent, laminary
or pulsating movement in or onto the shell, which has been
hea-ted to rolling temperature. In this manner, the deoxida-
tion agent is applied to the walls of the shell.
The process of the invention is carried out in such a
way that the deoxidation agent is used effectively in a dry
form as a powder having an average grain size o~ from 50 to
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1000 micrometers or as a granulate having an average grain
size of from 0.5 to 4 rnm in a supply container. As a rule,
the deoxidation agent is fed into a dosing apparatus by
gravity, if necessary with the support, for example, of a
shaker, by means of a rotating stirrer or by blowing in air,
in order to avoid the formation of a bridge of the powder.
The silo container can be developed possibly as a pressure
container and the material is then delivered by the action of
pressure.
The invention also provides an apparatus for the
processing o~ deoxidation agents according to the process o~
the invention. The apparatus has a supply container for the
deoxidation agent, and a volumetric or gravime-tric dosing
arrangement attached to it which empties into a pressure
container. The pressure container has an inlet for the
pressure gas and an outlet for the gas-deoxidation-agent
mixture. The outlet is controlled by an opening valve. The
apparatus includes a conveying line and delivery apparatus,
located on the end of -the conveying line, is used for the
gas-deoxidation-agent rnixture.
As the dosing apparatus, known dosing appara-tuses such
as dosing scales, dosing worms, dosing spirals, oscillating
chargers or a dosing~ribbon can be used. The dosing is
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carried out gravimetrically or volumetrically. Effectively
volumetric dosing is achieved; preferably a worm dosing
apparatus is used.
An embodiment of the invention will now be described,
by way of example, with reference to the accompanying
drawing, in which:
The Figure is a partially-cut away perspective view of
a preferred embodiment of the apparatus of the invention.
To effect the dosing, the deoxidation agent is first
inserted into a pressure container. The pressure container
is placed under pressure by means of a gasO Sui-table gases
include air, nitrogen CO2, an inert gas or a mixture of at
least two of such gases.
From 5 to 100 g of deoxidation agents are used per m of
the inside surface or inside wall of the shell. Effectively
from 10 to 60 g, advan-tageously from 25 to 50 g, of
deoxidation agent are used per m2 Of inside wall surface.
The volume of gas is from 50 to 750 standard liters per
kilogram of deoxidation agen-t. In an effective embodiment,
from 100 to 500 standard liters, preferably from 100 to 250
- 6 ~ LP 1337
standard liters, of gas are used per kilogram of
deoxidation agent. The pressure in the pressure container
is from 2 to 20 bar and preferably is from 2 to 10 bar.
After completion of the pressure loading of the
pressure container, the ~eoxidation agent can be
introduced into the working sequence of the
rolling mill. For this purpose, a conveying lin~ has
been provided which leads from the pressure container to
a delivery apparatus. The delivery apparatus can be,
for exampla, a simple pipe opening, a delivery cone,
possibly equipped with a spiral or with a diffuser, and
various types of nozzles~
In order to distribute and apply the deoxidation aqent
evenly in the hollow space of the shell, a circular,
laminary, turbulent or pulsating flow of the
gas~deoxidation-agent mixture is normally used - generally
a circular or turbulent flow is desired. Circular
movement means that the mixture moves while forming a
spiral-shaped movement right through the opening of the
shell. Laminar flow means that the mixture flows
through the opening of the workpiece in an essentially
even movement, whereas with t~~rbulent flow an eddy
effect of the flowing medium is sought. The pulsating
flow circumscribes a process according to which the
mixture is guided in several pressure surges through the
opening of the shell.
The delivery apparatus can be a-t-tached in the area
of the end of the shell, centrically as well as
eccentrically in relation to the opening of the shell.
However, the delivery apparatus can be moved into the
inside of the shell or the delivery apparatus can be
guided through the opening of the shell during the
delivery of the mixture.
During the use of the deoxidation agent, the shell
as a rule has a rolling temperature of about 1000 to
about 1300 C. Temperature changes may still occur between
the deoxidation process and the firs~ rolling process.
The process according to the invention is carried
out with an apparatus which is shown in the Figure, which
apparatus includes a supply container 1 for the deoxidation
agent, and a volumetric or gravimetric dosing arrangement 2,
which empties into a pressure container 3 and which i5
connected to the supply container 1. The pressure container
3 is equipped with a compressed gas feeder ~ and an outlet
5 for the gas-deoxidation-agent mixture. Outlet 5 is
controlled by means of a valve 6, whereby
after the opening of -the valve 6, the yas-deoxi~a-tion-
agen-t mix-ture is guided through a conveying line
7 to a delivery apparatus 8. Delivery appara-tus 8 at
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the same time functions as a distribution
arrangement and of guaranteeing an even, all-around
delivery.
A further, additional characteristic of pressure
container 3 is the formation or configuration of outlet
5. 1'he latter must ensure that the material is moved
out without leaving a residue and without segregation
during the operating rhythm. As a technical measure,
this can be achieved, for example, by means of a
pressure container having walls which incline very
steeply in the direction of outlet 5 and/or by a cone in
th~ area of outlet 5.
Additional embodiments involve the preheating of
the gas and/or of the descaling agent either in front of
or within pressure container 3 or in conveying line 7.
As a result of the relatively small quantities of
deoxidation agent and gas that are used, such preheating
is easily achieved.
By adaption of the dosing apparatus and of the
delivery apparatus of the invention, the deoxidation agent
can be processed in the same manner in a liquid form as
a solution, suspension or melt.
Customarily used and known types of construction
can be used as valves and control means for dosing
apparatus 9 and 10, compressed gas delivery 11 and
1P 1337
outlet 6. The control can be accomplished, for example,
mechanically, hydraulically, pneumatically or
electromagnetically, whereby a control adapted to the
operating rhythm of the rolling mechanism and the work
sequence can be performed manually mechanically or
electronically.
Furthermore, in the Figure, a shell, hollow block or
pipe 12 and the hollow space designated as inside space
13 of shell 12 are shown.
By using the process according to the invention,
one can successfully distribute the deoxidation agent in an
even distribution without possible segreqation in the
inside space of the shell, whereby the present layer
of scale is modified or ch~mically converted. As a
result of the use of the deoxidation agent, one usually
obtainc not only an even and well adhering, thin surface
layer, but the products formed on the inside surface of
the workpiece usually have non-abrasive or even
lubricating characteristics.
As a result of the use of small quantities of gas
as compared to the known descaling processes, in the
case of the use of air as a pressure gas, only
relatively small quantities of oxygen come ~nto contact
with the shell (heated to rolling temperature),
LP 1337
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which results in a considerably decreas~ ~nrmation
of new oxidation products. In the case of the use o
small quan-tities of qas it mav also he economically
justifiable to use inert gases, such as nitrogen or
inert gases. A reoxidation can thus be avoided.
As compared to the known processes for descaling,
smaller or relatively small quantities of deoxidation
agent are used per surface unit.
As a result of the small quantities of gas and
deoxidizing agent use~ in the process of the invention,
the previously proposed removal of the descaling gas
mixture by suction becomes superfluous. A flashback of
the mixture from the opening of the shell, as is
easily possible in the case of the processes which are
not conducted according to the invention, for example,
by a momentary strong heating up, does not occur at all
or, at most, in a nondisturbing manner. Whenever,
according to the process of the invention, the gas
and/or the deoxida-tion agent are preheated, these problems
can be ignored altogether. Furthermore, the chosen flow
pattern causes an extremely homogenous distribution
of the cleoxida~ion agent on the inner surface
of the shell so that no excessive amount of
deoxidatiQn agent is needed for the process. Such an
excessive amount would have to be separated again or
3~ 32
- 11 - LP 1337
counted as an economic loss.
By way of summary, the invention involves a process
for the processing of deoxidation agents and especially for
the deoxidation of shells for the production of a pipe
heated to a rolling temperature of from lO00~ to 1300 C. by
the application of a predetermined quantity of deoxidizing
agent by means of a predetermined quantity of gas as a
homogenous mixture into the inside walls, for example,
of a shell for the production of a seamless pipe.
The invention also involves an apparatus which includes
a supply container and a dosing arrangement for the
deoxidation agent. There is a pressure container which has
a gas supply, an inlet for the deoxidizing agent and an
outlet for the gas-deoxidation-agent mixture. The
apparatus fur-ther has a conveying line as well
as a delivery apparatu~.
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