Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to forming a flexible elongate
member of metal, the term "metal" as used in this specification
being employed in its broadest sense to include any metal or
metal alloy that can exist in rod or wire form.
S It is an object of the present invention to provide
an improved method of forming as a continuous process from
molten metal a flexible elongate metal member.
According to the invention the method comprises
causing molten metal contained in an upstanding, preferably
substantially vertical, tube to ejected out of the open upper
end of the tube whilst, at the same`time, establishing about
said open upper end an alternating electromagnetic field which
sets up forces such as to cause the ejected molten metal to be
compressed inwardly to form a column of molten metal which
protrudes from the open upper end of the tube; cooling said
column of molten metal to such an extent that at least an upper
end part of the column is in a substantially solid state; and,
whilst feeding molten metal into a lower part of the tube,
withdrawing the substantially solidified part of the column of
metal upwardly in the for~ of a continuous flexible elongate
metal member.
The alternating electromagnetic field established
about the open upper end of the tube induces eddy currents in
the molten metal being ejected out of the upper part of the
tube and the interaction between these eddy currents and the
electromagnetic field causes an electrodynamic force to be set
up, which force has the effect of causing the metal to compress
~~ inwardly and form a column of metal that protrudes from the
open upper end of the tube. The forces set up by the
alternating electromagnetic field may be such that, as
compared with the internal cross-sectional area of the tube,
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the cross-sectional area of the column of molten metal is
reduced to an extent that the flexible elongate metal member
that is continuously withdrawn upwardy from the tube is in rod
or wire form and requires no further change in cross-sectionai
shape and/or reduction in cross-sectional size. Alternatively,
the flexible elongate member that is withdrawn upwardly from
the tube may be in rod or other form of a shape and size
suitable for rolling down to rod form of smaller diameter or
for drawing down into wire.
Preferably molten metal is caused to be ejected out
of the open upper end of the tube by controlled continuous
feeding of molten metal into a lower part of the tube and
preferably the molten metal is fed into the tube from a
container of molten metal which is connected to but remote from
the tube and which constitutes, in effect, the other limb of a
U-tube. Molten metal may be fed at a controlled rate into the
container from a source of supply, for instance a holding
furnace. Preferably the surface area of the molten metal in
the container is substantially greater than the cross-sectional
area of the tube. Molten,metal may be continuously fed from
the container into the lower end of the tube under controlled
fluid pressure, e.g. air pressure, that is greater than
atmospheric pressure.
Cooling of the column of metal to suchan extent that --
at least an upper end part of the column is in a substantially
solid state may be effected by any convenient means but,
preferably, initial cooling of the column and withdrawal of
the column upwards from the alternating electromagnetic field
at the upper open end of the tube is effected by means of a
cold dummy member which is brought into contact with the upper
end of the column to cause the upper end to solidify and bond
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to the dummy member and to which is connected a flexible line
to haul-off means. The linear speed of withdrawal of the
flexible elongate member so formed, having regard to the rate
of cooling of the upper part of the column, will be such that
there is no risk that fracture of the column will occur in the
~ vicinity of the solidified or partially solidified part of the
_ column.
Preferably, on emerging from the alternating
electromagnetic field, the solidified upper part of the column
of metal and the succeeding flexible elongate metal member are
subjected to a cooling medium, fo~ example cold air or water
sprays.
The haul-off means may consist of or constitute a
part of a take-up device or it may serve to feed the flexible
elongate member to, or it may constltute a part of, treatment
or processing apparatus. The flexible elongate member may pass
directly to the haul-off means or, in travelling to the
haul-off means, pass through reducing rolls or other reducing
means and/or it may pass part way around one or more than one
guide roller. Where the cross-sectional area of the flexible
elongate member is reduced as it travels towards the haul-off
means, the haul-off means, and if a rotatably driven guide
roller or rotatably driven guide rollers is or are present the
or each guide roller, will each be driven at such a rotational
speed that the linear speed of the flexible elongate member
emerging from the upper end of the tube is substantially
constant.
The invention also includes apparatus for use in the
method of forming a flexible elongate total member, which
apparatus comprises at least one upstanding, preferably
substantially vertical, tube open at its upper end and
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connected at or near its lower end to a source of molten
metal; means, surrounding the open upper end of the tube, for
establishing an alternating electromagnetic field about said
open upper end, which means will set up forces that will cause
molten metal being ejected from said open upper end to be
compressed inwardly to form a column of molten metal protruding
~ from said upper end; means for cooling at least an upper end
part of the-column of molten metal; and means for withdrawing
upwardly a substantially solidified part of said column of
metal.
Preferably for initially cooling at least an upper
end part of the column of metal and for withdrawing the column
upwards a dummy member is provided which is of a shape and size
suitable for bringing into contact with the upper end of a
column of molten metal protruding from the upper open end of
the or each tube and which is connected by a flexible line to
haul-off means.
Preferably, the source of molten metal is a container
of molten metal remote from the tube or tubes and the lower end
of the or each upstanding tube is connected to an outlet in
the lower part of the container by a pipe, the or each tube,
associated pipe and container, in effect, constituting a
U-tube.
The means for establishing an alternating
electromagnetic field about the open upper end of the or each
tube preferably comprises an annular electromagnetic inductor
which can be positioned around the open upper end of the tube.
Preferably the cooling means for the column of metal
comprises a chamber housing cold air or water sprays.
The method and apparatus of the present invention
are especially suitable for use in forming rod or wire of
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- copper or copper alloy and of aluminium or aluminium alloy.
The invention provides several important advantages
that are not present in conventional methods of forming a
flexible elongate member in which a stream of molten metal is
arranged to flow downwardly from an outlet. in a lower part of
a container of molten metal. Firstly, the upstanding tube
from which the column of metal is drawn upwardly can be spaced
a substantial distance from the container or other source of
supply of molten metal with the result that cooling of metal,
e.g. by cooling water, is much safer than is the case when
cooling water is positioned below a container holding a large
quantity of molten metal. Secondly, should the column of metal
being withdrawn upwardly from the tube fracture for any reason
or should the source of power to the means establishing the
alternating electromagnetic field fail, little or no molten or
semi-molten metal will spill over the upper end of the
upstanding tube so that there is negligible risk to personnel.
Thirdly, since the upstanding tube can be spaced a substantial
distance from the container or other source of supply of molten
metal, a single container or other source can be employed to
feed molten metal to two or more upstanding tubes, upward
withdrawal of a column of metal from each tube being
independently controlled. Fourthly, the flexible elongate
metallic member can be directed to a take-up device or process
or treatment apparatus by passing the flexible member around
appropriate guide pulleys supported above the ground with a
consequential saving in floor space.
The invention is further illustrated by adescription,
by way of example, of the preferred method of and apparatus
for use in forming two flexible rods of copper with reference
to the accompanying diagrammatic drawings, in which:-
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Figure 1 is a diagrammatic representation of theapparatus, and
Figure 2 is a diagrammatic representation, on a
larger scale, of the preferred method of initially cooling and
withdrawing the rod.
Referring to the drawings, the apparatus comprises
a container 1 which contains molten copper C fed into the
container from a holding furnace 2. The container 1 is
surrounded by thermal insulation 3 and the copper in the
container is main~ained in the molten state at a temperature of
about 1150C by electrical heating coils 4. Two substantially
vertical tubes 6, positioned remote from the container 1, are
fed with molten copper from the container through pipes 7, one
end of each of which is connected to a lower part of the
container 1 and the other end of each of which is connected to
the lower end of one of the tubes 6. The pipes 7 are surrounded
by thermal insulation 8 and are heated by heating coils 9.
The upper open end of each vertical tube 6 is
surrounded by an annular electromagnetic inductor 11, the
upper part of the inducto~ being housed in the lower part of a
water cooling chamber 12. A guide pulley 14 is positioned
above each cooling chamber 12.
Each tube 6 has a bore of circular cross-section and
of a cross-sectional area of 100 sq. mm. The internal cross-
sectional area of the main body of the container 1 is 1.0 sq. m.
At the start of operations, the level of molten
copper C in the container 1 is such that the level of molten ',
copper in each of the tubes 6 is just below the upper open end
of the tube. A predetermined quantity of molten copper C is
now introduced into the container 1 from the holding furnace 2to form in the container 1 a sufficient head of molten copper
109098'~
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to cause molten copper to be ejected from the open upper end of
each tube 6 (Figure 2). At the same time, an alternating
current having a frequency of 500 kHz is caused to .flow through
each of the inductors 11 to establish an electromagntic field
about the open upper end of the associated tube 6 which sets up
forces such as to cause the ejected copper to be compressed
inwardly to form a column 20 of molten copper which protrudes
from the open end of the tube (Figure 2). With the column 20
of copper protruding from each tube held in this position, a
cold dummy member 15, attached to a flexible line (not shown)
connected to a haul-off device (not shown), is lowered into
contact with the upper end of the column 20 to cause the upper
. end part of the column to solidify and bond to the dummy member
at 21. When a firm bond has been obtained, the haul-off device
is brought into operation to draw th-e dummy member 15 and
solidified part of the column 20 upwardly whilst, at the same
time, molten copper is introduced from the holding furnace into
the container 1, the rate of feed of molten copper into the
container 1 and t.he speed of upward withdrawal of each of the
haul-off devices being such that a continuous flexible copper
rod 22 is drawn upwardly from each tube 6 through the cooling
chamber 12, where the rod is cooled by water sprays, and over
the pulley 14, without fracture of the column 2~--of molten
copper protruding from the tube.
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