Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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" CONTINUC)US EXTRUSION APPARATUS . '7
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D SCRIPTION.
This invention relates to apparatus
for the ~orming of metals by a continuous
extrusion process in which feedstock is
introduced into a circumferential groove in a
5. rotating wheel to pass into a passageway formed
between the groove and arcuate tooling extending
into the groove. The tooling includes an
orifice extending in a generally radial
direction from the groove to a die and an
10 o
abutment is provided to constrain the feedstock
to flow through the orifice and the die.
.In UK Patent Specification No. 1 566 152
there is described continuous extrusion
apparatus.having a rotatable wheel formed with
15. two identical circumferential grooves, arcuate
tooling with portions bounding radially outer
portions of the respective grooves provided with
exit apertures extending in a generally radial
direction from the respective grooves to a
20. single chamber of generally parallelepiped form
and one or more die orifices supplied from the
single chamber.
The die orifices are positioned in wall
portions of the single chamber of generally
25. parallelepiped form and discharge either through
an outer wall in a direction generally radially
; of the wheel or through side walls in a
: dire~tion generally parallel to the wheel axis.
With such a configuration with the dies
. 30. positioned in the walls, it is necessary to
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utilise bridge dies, that is die mandrels
supported on bridge webs located on the wall, to
produce tubular extrusions~ The presence o the
bridge webs gives rise to weld lines in the .
5. extrusion, which, on occasion, it is desirable
to avoid.
In a continuous extrusion apparatus
according to the present invention the exit
apertures Pxtend through a die top from the
10~ respective ~rooves to a substantially toroidal
chamber around a portal mandrel discharging
axially of the mandrel through a die orifice of
uninterrupted annular cross-section intermediate
the mandrel and a die body wall.
15. The invention will now be described, by
way of example r with reference to the
accompanying, partly diagrammatic, drawings, in
which:-
Figure 1 is a cross-sec~ional elevation of
20. continuous extrusion apparatus omitting de~ails
of a die portion;
Figure 2 is a cross-sectional elevation of
a die portion adapted to produce tube;
Figure 3 is a cross-section taken on the
25~ line III-III of Figure 2;
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Figure 4 is a cross-sectional elevation of
an alternakive die portion adapted to orm a
tubular cladding on a continuous core;
Figure 5 is a cross-section taken on the
5. line V~V of Figure 4;
Figure 6 is a cross-sectional elevation of
an alternative arrangement of a die portion
adapted to produce tube; and
Figure 7 is a cross-section taken on the
10. line VII-VII of Figure 6~
As shown in Figure 1, the continuous
extrusion apparatus includes a wheel 2 provided
with a pair of circumferential grooves 4 and is
mounted on a horizontal drive shaft S running in
15. bearings positioned on a bed 8. A shoe 10
mounted on a pivot 12 extending parallel to the
~horizontal drive shaft 6 carries tWQ sets of
arcuate tooling 14 registering with the
respective grooves 4 and is urged against a stop
20. 16 positioned adjacent the wheel 2 and above the
drive shaft 6 by means of a cam lever 18 bearing
against a shoulder 20 formed on the shoe. $ach
: ~ set of tooling 14 includes a shoe insert 22
(Figure 2) forming a closure to the adjacent
:; ~ 25. portion of the groove 4 and an abutment 24
extending into the groove to form an obturation
with a single die top 28 spanning the two
grooves.
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As shown in Figues 2 and 3, the die top 28
includes a pair of convex surfaces 30
registering with the respective grooves and each
penetrated by an exit aperture 32 leading to a
5. central, toroidal~ extrusion chamber 34 disposed
symmetrically of a radial plane intermediate the
grooves. A portal mandrel 26 is positioned by
means of a stub 27 in the die top 28 and extends
horizontally and parallel to a line tangential
10. to the wheel 2 co-axially through the extrusion
chamber 34 and a die body wall 35 to form an
uninterrupted extrusion orifice 38 discharging
through the face 40 of the die top.
In operation, to produce a tubular
15. extrusion/ a mandrel and die body appropriate to
the required tubular extrusion cross-section are
positioned in the die top 28, the shoe 10
pivoted into contact with the wheel 2 and the
cam lever 18 positioned to apply force to the
20. shoe. The drive is then energised and eedstock
introduced into the grooves to flow through the
respactive apertures 32 and into the extrusion
chamber 34. The flows from the respective
apertures combine in the extrusion chamber and
25. are extruded through the annular extrusion
orifice 38 to produce a continuous tubular
product.
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Since the path for the product from the
grooves 4 to the extrusion orifice 38 is
relatively short and free from discontinuities,
the product flows smoothly from the grooves to
5O the extrusion orifices with a minimum of
dissipation of energy. Accordingly the power
consumption of the process is restricted and
discontinuities in the extruded product are
avoided or reduced to a minimum.
lO. In the arrangement indicated in
conjunction with Figures 4 and 5, a hollow,
open-ended mandrel 42 is positioned with a
stepped rear end portion 43 co-acting with
correspondingly stepped bores 54 in the die
15. top 28. A core 44 to be clad is fed, in the
same direction as the direction of feed of the
feedstock, through the hollow mandrel 42
emerging at the annular extrusion orifice 38 to
receive a cladding of the extruded product 46.
20. In the arrangement shown the core has a plastics
material as an outer layer, which is sensitive
to elevated temperatures. Accordingly the
mandrel i5 provided with an internal cooling
shroud 48 to protect the core from the product
25. which immediately after extrusion i5 at a
temperature of about 450C. The product 46 is
extruded with an internal diameter greater than
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the e~ternal diameter of the core 44, to permit
the intervention of a portion the cooling
shroud 48 and is subjected to a stream of
cooling air, flowing initially intermediate the
5. product and the shroud and then to exhaust. To
this end a passage 50 is drilled in the shoe 10
to extend co-axially of the hollow, open ended,
mandrel 42. An outer sleeve 52 having the same
internal diameter as that of the mandrel 42 is
10. passed through the passage 50 and threaded into
the rear end portion 43 of the mandrel. A
spigot 56 is secured to the rear end 58 of the
outer sleeve to seat in a counter-bore 60 in the
shoe lO and is provided with a cooling air inlet
15. tapping 62 extending through the outer
sleeve 52. The tubular shroud 48 is positioned
internally co-axially of, and radially spaced
from, the outer sleeve 52 and is sealed to a
rear end portion 66 of the outer sleeve outward
20. of the cooling air inlet tapping. An
intermediate portion 68 of the shroud adjacent
the mandrel is of increased wall thickness with
axial lands 70 and grooves 72 formed in the
thickened portion, the lands 70 seating on the
25. interior of the mandrel 42 to support the shroud
and the grooves 72 permitting the flow of
coolin~ air. A forward portion 74 of the shroud
extends beyond the annular die orifice 38 by an
amount to provide a path of suficient length to
ensure the requisite transfer of heat from the
extruded product to the cooling air. T~e
cooling air exhausts to atmosphere through a
5. space 76 intermediate the interior of the shroud
and the core feed and through an internally
chamfered wall rear end portion 78 of the
shroud. Swaging means (not shown~ are provided
to effect swaging down of the extruded cladding
10. product 46 on to the cor~ 44 beyond the forward
portion 74 of the shroud.
In a further alternative arrangement
indicated in Figures 6 and 7, where it is not
required to feed a core to the interior of a
15. tubular extrusion 94, extrusion is effected along a
horizontal axis passing through the wheel axis,
that ~s, along a radial axis. Thus the shoe 10
carries two sets of tooling 14 with the
abu~ment 24 of each positioned slightly below
20. the horizontal central plane passing through the
wheel axisO Exit apertures 80 from convex
suraces of the die top 28 registering with the
grooves 4 extend horizontally with diverging
passageways 81 toward a central, toroidal,
250 extru~ion chamber 82. A portal mandrel 84
positioned by means of a stepped stub portion 85
in the die top extends horizontally adjacent the
wheel along an axis radial to the wheel
co-axially of the extrusion chamber and a die
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body wall adjacent the extrusion chamber to form
an uninterrupted annular extrusion orifice 86
discharging through the face 88 of the die top
remote from the wheel. The por~al mandrel is
5. formed with a circumferential, arcuate section,
groove 90 defining a portion of the extrusion
chamber wall.
In operation, ~o produce a tubular
extrusion, as previously, the appropriate
10. mandrel 84 and die body 92 are positioned in the
die top 28, the shoe 10 positioned in contact
with the wheel 2, the drive energised and feed
established to the two grooves. The flows from
the respective apertures 80 combine in the
15. extrusion chamber 82 and are extruded through
the annular extrusion orifice 86 to produce a
continuous tubular product. It will be
appreciated that the length of the diverging
passageways 81 connectiny the grooves 4 to the
20. extrusion chamber 82 and extrusion orifice 86 is
short and does not involve substantial
discontinuities or changes in direction of flow
of the product. Thus a minimum of energy is
dissipated thereby minimising the power
25. requirements and making for the production of
tubular extrusions free from undesirable
discontinuities.
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It will be appreciated that, :in each of
the arrangements, passages may be provided in
the die top and, in instances where an otherwise
solid portal mandrel is utilised, in the
5. mandrel, for the flow of cooling liquid to
effect extraction of heat from the various
components and avoid temperatures in the
components exceeding desirable working limits.
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