Note: Descriptions are shown in the official language in which they were submitted.
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EXTRUSION PRESS DIE ASSEMBLY
Background
[0001] Tubing material, such as metal piping formed from copper, aluminum,
metal alloy,
or other metals, is often manufactured by extrusion processes. In an extrusion
process, a
large block of metal, referred to as a billet, is worked through a die
structure having a circular
or other configuration with an opening smaller than the size of the billet
used to form the
tubing material. The billet may be pre-heated to a high temperature before a
piercing rod is
forced through the center of the billet to form a channel therethrough. A
large pressure,
typically on the order of 1,000 to 100,000 pounds-per-square-inch, is then
applied to the billet
to force the pre-heated material over the piercing rod and through the die
opening. The
pressure forces the material to deform and extrude, exiting the back of the
die as a tube
having a diameter similar to the diameter of the opening of the die.
[0002] In order to produce large quantities of metal tubing by extrusion,
large billets and
manufacturing machinery are required, and billets used in extrusion processes
to create metal
tubing often reach or exceed 1,000 pounds in weight. The size of the machines
and billets
requires large manufacturing facilities to produce the tubing, and the size
requirements of the
extrusion process lead to large start-up and maintenance costs for the
manufacturing
operation. Furthermore, limitations of the processes, such as extruding only
one billet at a
time, lead to inefficiencies from billet sizes.
Summary
[00031 Disclosed herein are systems, devices and methods for extruding
materials using a
rotating extrusion press die assembly. In certain embodiments, the systems,
devices and
methods allow for continuous extrusion of a plurality of material billets.
Such continuous
extrusion allows for relatively smaller billets to be efficiently used to
produce a desired
quantity of extruded material, and therefore the scale and size requirements
of such
continuous extrusion press systems can be smaller than conventional extrusions
processes.
[0004] In one aspect, a die assembly for extruding a material includes a
plurality of die
plates coupled together to form a die body. The die body has a passage
defining an entrance
and an exit, and the diameter of the exit is smaller than the diameter of the
entrance. A
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tapered surface is located between the entrance and the exit. Each of the die
plates has a
center bore with a tapered interior surface around the center bore, and an
interior surface of a
center bore in a first die plate is tapered at a smaller angle relative to an
axis of the passage
than an interior surface of a center bore in a second die plate positioned
adjacent to a front
face of the first die plate. A base is coupled to the die body, and rotation
of the base causes
the die body to rotate.
[0005] In certain implementations, the second die plate is positioned nearer
to the entrance
of the die body than the first die plate. The die assembly may include a third
die plate having
a center bore with an interior surface that is tapered at a larger angle
relative to the axis than
an interior surface of a center bore in a die plate positioned adjacent to a
front face of the
third die plate. The die plate positioned adjacent to the front face of the
third die plate may
be the first die plate, and the third die plate may be positioned nearer to
the exit of the die
body than the first die plate.
[0006] In certain implementations, the die assembly includes a third plate
that forms a
portion of the die body, and the third plate has a central bore with an
interior surface around
the center bore that is not tapered at an angle relative to the axis of the
passage. The center
bore of the third plate defines the entrance of the die body. In certain
implementations, the
base includes a center bore, and the center bore of the base has a diameter
that is greater than
a diameter of the die body exit.
[0007] In certain implementations, the die body is configured to receive a
billet of material
for extrusion, and the billet is not pre-heated before entering the die body.
Rotation of the die
body creates friction between the tapered interior surface and a billet
advanced through the
entrance and into the interior passage of the die body. The friction heats the
billet to a
temperature that is sufficient to cause deformation of the billet material,
and the heated billet
is deformable under a deformation force that does not exceed mechanical
property limits of
the billet material. Friction between the billet and a mandrel over which the
billet is
advanced heats the billet and the mandrel. A cooling system provides cooling
fluid to an
interior portion of the mandrel.
[0008] In certain implementations, at least one of the die plates is formed
from two
different materials, with a first material forming a perimeter of a bore in
the die plate and a
second material forming an outer portion of the die plate. At least one of the
first and second
materials is a ceramic material, a steel, or a consumable material. In certain
implementations,
a front face of the die body near the entrance is configured to mate with a
centering insert
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having a diameter substantially equal to the diameter of the entrance. The
centering insert
and a perimeter of the entrance are formed from the same material.
[0009] In certain implementations, the die body is configured to receive a
mandrel tip
through the entrance such that the mandrel tip is positionable within the
interior passage of
the die body. The interior surface of the die body includes a complementary
portion having
an angle that corresponds to an angle of an outer surface of the mandrel tip.
The die body is
configured to receive a billet pressed through the interior passage of the die
body to form an
extruded product, the extruded product having an outer diameter corresponding
to the
diameter of the exit of the die body and an inner diameter corresponding to a
diameter of the
mandrel tip.
[00101 In one aspect, a die assembly includes a means for extruding a material
that includes
a plurality of plate means. The means for extruding has a passage means
defining an
entrance and an exit of the means for extruding, and the diameter of the exit
is smaller than
the diameter of the entrance. The means for extruding also has a tapered
surface means
between the entrance and the exit. Each of the plate means has a center bore
with a tapered
surface around the center bore, and an interior surface of a center bore in a
first plate means is
tapered at a smaller angle relative to an axis of the passage means than an
interior surface of a
center bore in a second plate means positioned adjacent to a front face of the
first plate
means. The die assembly also includes a means for coupling the means for
extruding to a
rotation means, and rotation of the means for coupling causes the means for
extruding to
rotate.
[00111 In certain implementations, the second plate means is positioned nearer
to the
entrance of the means for extruding than the first plate means. The means for
extruding may
include a third plate means having a center bore with an interior surface that
is tapered at a
larger angle relative to the axis than an interior surface of a center bore in
a plate means
positioned adjacent to a front face of the third plate means. The plate means
positioned
adjacent to the front face of the third plate means may be the first plate
means, and the third
plate means may be positioned nearer to the exit of the means for extruding
than the first
plate means.
[0012] In certain implementations, the die assembly includes a third plate
means that forms
a portion of the means for extruding, the third plate means having a central
bore with an
interior surface around the center bore that is not tapered at an angle
relative to the axis. The
center bore of the third plate means defines the entrance of the means for
extruding. In
certain implementations, the means for coupling includes a center bore. The
center bore of
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the means for coupling has a diameter that is greater than a diameter of the
exit of the means
for extruding.
[0013] In certain implementations, the means for extruding is configured to
receive a billet
of material for extrusion, and the billet is not pre-heated before entering
the means for
extruding. Rotation of the means for extruding creates friction between the
tapered surface
means and a billet advanced through the entrance and into the passage means of
the means
for extruding. The friction heats the billet to a temperature that is
sufficient to cause
deformation of the billet material. The heated billet is deformable under a
deformation force
that does not exceed mechanical property limits of the billet material.
Friction between the
billet and a rod means over which the billet is advanced heats the billet and
the rod means,
and a means for cooling provides cooling fluid to an interior portion of the
rod means.
[0014] In certain implementations, at least one of the plate means is formed
from two
different materials, with a first material forming a perimeter of a bore in
the plate means and
a second material forming an outer portion of the plate means. At least one of
the first and
second materials is a ceramic material, a steel, or a consumable material. In
certain
implementations, a front face of the means for extruding near the entrance is
configured to
mate with a means for centering a billet, the means for centering having a
diameter
substantially equal to the diameter of the entrance. The means for centering
and a perimeter
of the entrance are formed from the same material.
[0015] In certain implementations, the means for extruding is configured to
receive a rod
tip means through the entrance such that the rod tip means is positionable
within the interior
passage of the means for extruding. The tapered surface means of the means for
extruding
comprises a complementary portion having an angle that corresponds to an angle
of an outer
surface of the rod tip means. The means for extruding is configured to receive
a billet
pressed through the passage means of the means for extruding to form an
extruded product,
the extruded product having an outer diameter corresponding to the diameter of
the exit of the
means for extruding and an inner diameter corresponding to a diameter of the
rod tip means.
[0016] Variations and modifications of the embodiments discussed herein will
occur to
those of skill in the art after reviewing this disclosure. The foregoing
features and aspects
may be implemented in any combination and sub-combination, including multiple
dependent
combinations, and sub-combinations with one or more other features described
herein. The
various features described or illustrated herein, including any components
thereof, may be
combined or integrated in other systems. Moreover, certain features may be
omitted or not
implemented.
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Brief Description of the Drawings
[0017] The foregoing and other objects and advantages will be apparent upon
consideration
of the following detailed description, taken in conjunction with the
accompanying drawings
in which like-referenced characters refer to like parts throughout.
[0018] Figure 1 shows a perspective view of an illustrative extrusion press
die assembly.
[0019] Figure 2 shows a side elevation view of an illustrative extrusion press
system.
[0020] Figure 3 shows a side elevation view of the extrusion press die
assembly of Figure
1.
[0021] Figure 4 shows an illustrative steel end holder of the extrusion press
die assembly of
Figure 1.
[0022] Figure 5 shows an illustrative entry plate of the extrusion press die
assembly of
Figure 1.
[0023] Figure 6 shows an illustrative first intermediate plate of the
extrusion press die
assembly of Figure 1.
[0024] Figure 7 shows an illustrative second intermediate plate of the
extrusion press die
assembly of Figure 1.
[0025] Figure 8 shows an illustrative exit plate of the extrusion press die
assembly of
Figure 1.
[0026] Figure 9 shows an illustrative base plate of the extrusion press die
assembly of
Figure 1.
[0027] Figure 10 shows an illustrative cross-section view of the extrusion
press die
assembly of Figure 1.
[0028] Figure 11 shows an illustrative mandrel bar tip.
[0029] Figure 12 shows an illustrative cross-section of the extrusion press
die assembly of
Figure 1 with the mandrel bar tip of Figure 11 advanced into the die assembly.
[0030] Figure 13 shows a cross-sectional view of the die assembly and mandrel
bar tip of
Figure 12 during extrusion of a material.
Detailed Description
[0031] To provide an overall understanding of the systems, methods, and
devices described
herein, certain illustrative embodiments will be described. Although the
embodiments and
features described herein are discussed for use in connection with extrusion
press systems, it
will be understood that the components, connection mechanisms, manufacturing
methods,
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and other features outlined below may be combined with one another in any
suitable manner
and may be adapted and applied to systems to be used in other manufacturing
processes.
Furthermore, although the embodiments described herein relate to extruding
metal tubing
from hollow billets, it will be understood that the systems, devices, and
methods described
herein may be adapted and applied to systems for extruding any suitable type
of material.
[0032] Figure 1 shows a die assembly 1 for forming extruded tubing, which may
include
seamless extruded tubing, in a press extrusion system. The die assembly 1 may
provide for
continuous extrusion of a plurality of billets to produce a seamless extruded
tubing product
according to various seamless tubing standards including, for example, the
ASTM-B88
Standard Specification for Seamless Copper Water Tube. The seamless extruded
tubing may
also comply with the standards under NSF/ANSI-61 for Drinking Water System
Components. The die assembly 1 includes a mandrel bar 10 over which material
billets, such
as billet 17, are passed in the direction of arrow A and through the die
assembly to form an
extruded tubing product. The billet 17 may be formed from any suitable
material for use in
extrusion press systems including, but not limited to, various metals
including copper and
copper alloys, or any other suitable non-ferrous metals such as aluminum,
nickel, titanium,
and alloys thereof, ferrous metals including steel and other iron alloys,
polymers such as
plastics, or any other suitable material or combinations thereof. The billets
passing over the
mandrel bar 10 are advanced through a centering insert 9 and a die body 18,
which is
composed of a stack of die plates 3-7 and a base plate 8, and through a
cooling system 13 to
form the tube product. While die assembly 1 includes five plates coupled to a
base plate, a
die assembly may include more plates or fewer plates, and a die body may be
longer or
shorter than the die body 18 in certain applications.
[0033] During extrusion, the die body 18 rotates while billet 17 is pressed
through the die
body. The billet 17 is held by grippers 44 of the centering insert 9, which
does not rotate, and
thus the billet 17 does not rotate as it enters the rotating die body 18 at
the entrance 11 to the
center passage through the die body. The rotation of the die body 18 creates
friction with the
outer surface of the non-rotating billet 17 as it is pressed through the die,
and the friction
heats the billet 17 to a temperature sufficient for the billet material to
deform. For example, a
metal billet may be heated by the friction to a temperature greater than 1000
F for
deformation. The temperature requirements of different materials and different
metals may
vary, and billet temperatures less than 1000 F may be suitable in some
applications. In
contrast to other extrusion systems, the die assembly 1 does not require pre-
heating of billets
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before extrusion, as the rotation of the die body 18 and the friction created
by contact with the
non-rotating billet 17 provide energy that heats the billet to a deformable
temperature.
100341 The die assembly 1 may be used for forming an extruded material in any
suitable
extrusion system, including, for example, the extrusion press system described
in U.S. Patent
Application No. 13/650,977, filed October 12, 2012. For example, the die
assembly 1 may be
implemented in the extrusion press system 57 shown in Figure 2 for continuous
material
extrusion. The extrusion press system 57 includes a mandrel carriage section
58 and a platen
structure section 59. The mandrel carriage section 58 includes a mandrel bar
74, water
clamps or cooling elements 60 and 61, mandrel grips or gripping elements 62
and 63, and a
billet delivery system. The mandrel carriage section 58 is supported by a
physical carriage
structure, which is not shown in Figure 2 to avoid overcomplicating the
drawing, but which
carriage structure serves as a mount for the components of the mandrel
carriage 58. The platen
structure section 59 includes an entry platen 65 and a rear die platen 66,
press-ram
platens 67 and 68, a centering platen 69, and a rotating die 70 that presses
against the rear die
platen 66. The platen structure section 59 is supported by a frame 71 that
also serves as a mount
for the motor 72 and related gearbox components (not shown). The direction
along which billet
loading, transport, and extrusion occurs according to the extrusion press
system 57 is denoted by
arrow B. The extrusion press system 57 may be operated, at least in part, by
a PLC system that controls aspects of the billet delivery subsystem 77,
extrusion subsystem
78, and a cooling subsystem of the extrusion press system 57
100351 The mandrel grips 62, 63 comprise a mandrel bar gripping system 73
designed to
hold the mandrel bar in place while allowing a plurality of billets to be
continuously fed along
and about the mandrel bar 74 to provide for continuous extrusion. The mandrel
grips
62, 63 may be controlled by the PLC system to securely hold in place and
prevent the
mandrel bar 74 from rotating such that at any given time during the extrusion
process, at least one
of the mandrel grips 62, 63 is gripping the mandrel bar 74. The mandrel grips
62, 63 set the
position of the mandrel bar 74 and prevent the mandrel bar 74 from rotating.
When the mandrel
grips 62, 63 are in a gripping position, thereby gripping the mandrel bar 74,
the
mandrel grips 62, 63 prevent billets from being transported along the mandrel
bar 74 through
the grips.
100361 The mandrel grips 62, 63 operate by alternately gripping the mandrel
bar 74 to allow one
or more billets to pass through a respective mandrel grip at a given time. For
example, the
upstream mandrel grip 62 may release the mandrel bar 74 while the downstream
mandrel
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grip 63 is gripping the mandrel bar 74. At any given time, at least one of the
mandrel
grips 62, 63 is preferably gripping or otherwise engaged with the mandrel bar
74. One or
more billets queued or indexed near the upstream mandrel grip 62, or being
transported along
the mandrel bar 74, may pass through the open upstream mandrel grip 62. After
a specified
number of billets have passed through the open upstream mandrel grip 62, the
mandrel
gripper 62 may close and thereby return to gripping the mandrel bar 74, and
the billets may
be advanced to the downstream gripping element 63. The downstream gripping
element 63
may remain closed, thereby gripping the mandrel bar 74, or the downstream
mandrel grip 63
may open after the upstream mandrel grip 62 re-grips the mandrel bar 74.
Although two
mandrel grips 62, 63 are shown in the extrusion press system 57, it will be
understood that
any suitable number of mandrel grips may be provided.
[0037] The water clamps 60, 61 comprise a mandrel bar water delivery system 75
designed
to supply cooling water along the interior of the mandrel bar 74 to the
mandrel bar tip during
the extrusion process. The water clamps 60, 61 may be controlled by the PLC
system to
.. continuously supply process cooling water to the mandrel bar during the
extrusion process
while allowing a plurality of billets to be continuously feed along and about
the mandrel
bar 74. The water clamps 60, 61 operate such that there is no or substantially
no interruption
to the supply of process cooling water to the mandrel bar tip during the
extrusion process.
Similar to the operation of the mandrel grips 62, 63 discussed above, when the
water clamps
60, 61 are clamped to or engaged with the mandrel bar 74, the water clamps 60,
61 prevent
billets from being transported along the mandrel bar 74 through the water
clamps.
[0038] The water clamps 60, 61 operate such that at any given time during the
extrusion at
least one of the water clamps is clamped to or engaged with the mandrel bar 74
and thereby
delivers cooling water into the mandrel bar 74 for delivery to the tip of the
mandrel bar.
.. When a billet passes through one of the water clamps 60, 61, the respective
water clamp
discontinues delivering cooling water and releases or disengages the mandrel
bar 74 to allow
the billet to pass therethrough before re-clamping the mandrel bar 74 and
continuing to
deliver cooling water. While one of the water clamps 60, 61 is unclamped or
disengaged
from the mandrel bar 74, the other water clamp continues to deliver cooling
water to the
mandrel bar.
[0039] For example, the upstream water clamp 60 may release the mandrel bar 74
while the
downstream water clamp 61 is clamped to the mandrel bar 74. At any given time,
at least one
of the water clamps 60, 61 is preferably clamped to the mandrel bar 74 to
continuously
deliver cooling water. One or more billets queued or indexed near the upstream
water
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clamp 60, or being transported along the mandrel bar 74, may pass through the
open
upstream water clamp 60. After a specified number of billets has passed
through the open
upstream water clamp 60, the water clamp 60 may close and thereby return to
clamping the
mandrel bar 74 and delivering cooling water, and the billets may be advanced
to the
downstream water clamp 61. The downstream water clamp 61 may remain closed,
thereby
clamping the mandrel bar 74, or the downstream water clamp 61 may open after
the upstream
water clamp 60 re-clamps to the mandrel bar 74. Although two water clamps 60,
61 are
shown in the extrusion press system 57, it will be understood that any
suitable number of
water clamps may be provided.
[0040] The mandrel bar 74 extends along substantially the length of the
extrusion press
system 57 and is positioned to place the mandrel bar tip through the rotating
die 70. The
rotating die 70 may incorporate the die body 18 shown in Figure 1. The
adjustment to
properly position the mandrel bar tip through the die 70 is accomplished by
moving the
mandrel carriage section 58, thus moving the mandrel bar 74. The adjustments
to the
mandrel bar 74 and the mandrel carriage section 58 may be towards or away from
the die 70.
The mandrel bar 74 and the mandrel carriage section 58 preferably cannot be
adjusted while
the extrusion press system 57 is in operation, although it will be understood
that in certain
embodiments the mandrel bar 74 and/or mandrel carriage section 58 may be
adjusted during
operation.
.. [0041] As discussed above, the extrusion press system 57 includes a platen
structure
section 59 having an entry platen 65 and a rear die platen 66, press-ram
platens 67 and 68, a
centering platen 69, and a rotating die 70 presses against the rear die platen
66. Near the
entry platen 65 is the press-ram platen assembly 76 that includes a first
press-ram platen 67,
or A-Ram, and a second press-ram platen 68, or B-Ram. The first and second
press-ram
platens 67, 68 feed billets into the centering platen 69, which grips the
billets and prevents the
billets from rotating prior to entering the rotating die 70, which presses
against the rear die
platen 66.
[0042] The press-ram platens 67, 68 operate by gripping the billets and
providing a
substantially constant pushing force in the direction of the extrusion die
stack 70. At any
given time at least one of the press-ram platens 67, 68 grips a billet and
advances the billet
along the mandrel bar 74 to provide the constant pushing force. The press-ram
platens 67, 68
form the final part of the billet delivery subsystem 77 before the billet
enters the centering
insert 69 and the rotating die 70 of the extrusion subsystem 78. Similar to
the billet feed
track section before the entry platen 65, the section prior to the press-ram
platens 67, 68
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preferably continuously indexes the billets to minimize any gaps between a
billet that is
gripped by the press-ram platens 67, 68 and the next billet.
[0043] As discussed above, the press-rams 67, 68 continuously push billets
into the rotating
die 70. The press-rams 67, 68 alternate gripping and advancing billets towards
and into the
rotating die 70 and then ungripping the advanced billets and retracting for
the next
gripping/advancing cycle. There is preferably an overlap between the time when
one press-
ram stops pushing and the other press-ram is about to start pushing so that
there is always
uniform pressure on the rotating die 70. The press-rams 67, 68 advance and
retract via press-
ram cylinders coupled to the respective press-ram. As shown there arc two
press-ram
cylinders 79, 80 per press-ram. A first set of press-ram cylinders 80 is
located on the left and
right of the entry platen 65 (although the right-side press-ram cylinder is
hidden from view
behind the left-side press-ram cylinder). The first set of press-ram cylinders
80 couples with
the first press-ram platen 67 and is configured to move the first press-ram 67
as the first
press-ram 67 advances billets and retracts to grab a following billet. A
second set of press-
ram cylinders 79 is located to the top and bottom of the entry platen 65. The
second set of
press-ram cylinders 79 couples with the second press-ram platen 68 and is
configured to
move the second press-ram 68 as the second press-ram 68 advances billets and
retracts to
grab a following billet. Although two press-ram cylinders are shown for each
of the first and
second press-ram platens 67, 68, it will be understood that any suitable
number of press-ram
cylinders may be provided, and in certain embodiments press-ram cylinders may
be coupled
to both the first and second press-rams 67, 68.
[00441 The centering platen 69 receives billets advanced by the press-rams 67,
68 and
functions to hold the billets during the extrusion process prior to entry of
the billets into the
rotating die 70. When the centering platen 69 is positioned in place for the
extrusion process,
the centering platen 69 substantially becomes part of the extrusion die 70.
That is, a
centering insert of the centering platen 69 substantially abuts the rotating
die 70. The
centering platen 69 itself, however, and the components therein including the
centering insert,
do not rotate with the rotating die 70. The centering platen 69 prevents the
billets that are no
longer held by the second press-ram from rotating while the die 70 rotates by
gripping the
billets and thereby preventing the billets from rotating prior to entry of the
billets into the
rotating die 70.
[0045] Referring back to the die assembly 1 of Figure 1, when the assembly is
used in an
extrusion process, for example in the extrusion system of Figure 2, the
centering insert 9 is
advanced to the front edge of the die body 18, such that a front surface 55 of
the centering
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insert 9 contacts a front surface 16 of the die body 18. This orientation of
the die body 18
and the centering insert 9 during extrusion is shown in Figure 3. In this
orientation, the
contact between the faces 55 and 16 of the centering insert 9 and die body 18,
respectively,
prevents material from escaping the die body 18 during the extrusion process.
To begin the
extrusion, a billet 17 is advanced over the mandrel bar 10 in the direction of
arrow A and
through the die assembly 1 to press the billet 17 into an extruded tube
product. Before
entering the die assembly 1, the billet 17 is advanced into the opening 15 of
the centering
insert 9, where grippers 44 engage the outer surface of the billet 17. As the
billet 17 is
advanced through the opening 15, these grippers 44 prevent rotation of the
billet 17 when the
billet 17 is contacted by the rotating interior surface 14 of the die body 18.
[00461 While the billet 17 and centering insert 9 do not rotate during the
extrusion process,
the die body 18 and base plate 8 to which the die body is connected are
rotated by the motor-
driven spindle 56. As the billet 17 is advanced through the centering insert
9, it passes
through the entrance 11 of the die body 18 and contacts the interior surface
14 of the die body
18. A torsional force is applied to the outer surface of the billet 17 due to
the interference
contact between the rotating die 18 and the billet 17. The grippers 44 of the
centering insert 9
resist this torsional force and prevent the billet 17 from rotating before it
enters the die body
18, creating friction and producing the energy that heats the billet 17.
[00471 The profile of the tapered interior surface 14 of the die body 18 is
defined by the
shape and orientation of central bores that pass through the plates in the die
body 18. The die
body 18 is formed of a stack of die plates, including a steel end holder 3, an
entry plate 4, a
first intermediate plate 5, a second intermediate plate 6, and an exit plate
7. This series of
plates that makes up the die body 18 are stacked together, secured to one
another by a
fastener, such as the bolt 2 in Figure 1, and connected to the base plate 8.
The bolt 2 is placed
into each of the through-holes 12, which pass through each of the plates 3-8.
The base plate 8
is then coupled to motor-driven spindle 56, which rotates the plate 8, as well
as the plates 3-7
of the die body 18. In certain implementations, a die body may be employed
that includes
more or fewer than the five plates 3-7 shown in die body 18.
[00481 The interior surface 14 created by the central bores of the plates of
the die body 18
exhibits a tapered profile that narrows the interior passage through the die
body 18 from the
entrance 11 to an exit of the passage at the exit plate 7. Thus, when force is
applied to the
billet 17 to press the billet through the die body 18, the material of the
billet 17 is extruded as
the outer diameter of the material is forced to decrease to pass through each
of the plates 3-7.
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The dimensions of the plates 3-7, and the interaction between the interior
surface 14 and the
billet 17, is described in more detail below with respect to Figures 4-13.
[0049] Figures 4-9 show each of the plates 3-7 in the die body 18, and the
base plate 8 to
which the die body 18 is connected. Figure 4 shows the steel end holder 3 of
the die body 18
that forms the front face 16 of the die body and the entrance 11 to the
interior passage of the
die body. The steel end holder 3 includes a central circular bore 21 that
defines the diameter
of the opening entrance 11 when stacked in the die body 18. As shown in Figure
4, the steel
end holder 3 is formed from two materials, with the outer perimeter 19 of the
plate formed
from one material and the perimeter 20 of the bore 21 formed from a different
material. The
two materials that make up the steel end holder 3 may be chosen to form
complementary
interfaces between the steel end holder 3 and both the centering insert 9 and
the entry plate 4.
For example, the outer perimeter 19 may be formed of a steel, such as H13
steel, that is the
same as or similar to the material that forms an outer perimeter of the entry
plate 4, while the
bore perimeter 20 may be formed of a different material, such as an inconel
steel, that is the
same as or similar to the material used to form the centering insert 9. By
matching the
material of the bore perimeter 20 and the centering insert 9, the front face
23 of the bore
perimeter 20 that contacts the front face 55 of the centering insert 9
provides a
complementary interface that reduces wear when the die assembly 1 is in use.
Because the
die body 18 rotates and the centering insert 9 remains stationary, friction
may be created
between the face 23 and the face 55. By forming the bore perimeter 20 and the
centering
insert 9 from the same material or similar materials, along with adjusting the
pressure of
surface 55 against surface 16, the wearing effect of this friction can be
minimized,
particularly during start up and shut down of the extrusion process when
rotation of the die
body 18 starts or stops.
[0050] The second plate in the die body 18 is the entry plate 4, shown in
Figure 5. As with
the steel end holder 3, the entry plate 4 is formed from two different
materials. One material
forms the outer perimeter 25 of the plate while a second material forms the
bore perimeter 24
around the central bore 26 through the center of the plate. The outer
perimeter 25 may be
made of the same material or a similar material as the outer perimeter of the
steel end holder
3, for example H13 steel material. The perimeter 24 of the bore 26 is formed
from a wear-
resistant material, for example a ceramic material, that resists degradation
when a billet, such
as billet 17, is pressed through the bore 26 and contacts the interior surface
27.
[0051] The entry plate 4 begins the taper of the interior surface 14 of the
die body 18 from
the entrance 11 to the exit of the die body. The interior surface 27 of the
perimeter 24 is
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angled such that the diameter across the diameter of the center bore 26 is
greater at the front
face of the plate 4 that abuts the back face of the steel end holder 3 and
smaller at the back
face of the entry plate 4 that abuts the first intermediate plate 5. When
billet 17, having a
diameter that is equal to the diameter of the bore 26 at the front face, is
pressed through the
entry plate 4, the tapering of the surface 27 creates friction between the
rotating plate 4 and
the billet 17. This friction generates energy that heats the billet 17 as it
is advanced into the
rotating die body 18, beginning the deformation of the billet through the
tapered interior
surface 14. In contrast to extrusion processes in which contact between a pre-
heated billet
and a non-rotating die creates heat energy as a by-product, the friction
heating of the non-pre-
heated billet 17 is necessary for extrusion as it is needed to heat the billet
to a temperature
adequate for deformation.
[0052] Figure 6 shows the first intermediate plate 5 that is located behind
the entry plate 4
in the stack of plates that make up the die body 18. The first intermediate
plate 5 includes an
outer perimeter 29, formed from a first material, and a bore perimeter 28,
formed from a
second material. The outer perimeter 29 may be formed of the same materials or
similar
materials as the outer perimeters of the other plates in the stack, for
example an H13 steel.
Perimeter 28 of the center bore 30 through the plate is formed from a wear-
resistant material,
for example a ceramic material, as discussed with respect to bore perimeter 24
of the entry
plate 4. The inner surface 31 of the bore perimeter 28 is tapered from the
front face of the
first intermediate plate 5 that abuts the entry plate 4 in the stack to the
back face of the first
intermediate plate 5 that abuts the second intermediate plate 6 in the plate
stack. The angling
of the inner surface 31 tapers the center bore 30 from the front face to the
rear face and
further tapers the interior passage and surface 14 of the die body 18, as
discussed above with
respect to the center bore 26 of the entry plate 4.
[0053] The degree at which the inner surface 31 tapers with respect to a
center axis of the
central bore 30 in the first intermediate plate 5 relative to the taper angle
of the inner surface
27 of the entry plate 4 is dependent on the material being extruded and the
total overall
number of die plates. In certain implementations for a particular material,
the degree at
which the inner surface 31 tapers may be less than the taper angle of the
inner surface 27 of
the entry plate 4. This change in the angle of the inner surface and the
smaller diameter of
the center bore 30 relative to the center bore 26 may spread the frictional
interface with the
billet 17 and the work required to deform the billet 17 more evenly over the
entry plate 4 and
the first intermediate plate 5, reducing material wear and extending the
lifetime of the die
plates as well as improving concentricity and uniformity of an extruded
product. This
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spreading of work and frictional force and the correlation between materials
and the degree of
surface tapering is discussed more fully below with respect to the cross
sections shown in
Figures 10, 12 and 13.
[00541 The second intermediate plate 6, which follows the first intermediate
plate 5 in the
die stack, is shown in Figure 7. Similar to plates 3-5, the second
intermediate plate 6 has an
outer perimeter 32, formed of a first material, and a perimeter 33 around a
center bore 34,
formed of the second material. The first material that forms outer perimeter
32 may be the
same as or similar to the other plates in the stack, for example an H13 steel,
and the material
that forms the bore perimeter 33 may be a wear-resistant material, such as a
ceramic. The
interior surface 35 of the perimeter 33 around the central bore 34 is angled
from a front face
of the plate 6 that abuts the first intermediate plate 5 to a back face of the
plate 6 that abuts
the exit plate 7.
[00551 The final plate in the plate stack that makes up the die body 18 is the
exit plate 7,
which is shown in Figure 8. The exit plate 7, similar to plates 3-6, has an
outer perimeter 36
formed from a first material, such as an H13 steel, and a perimeter 37 around
a central bore
38 formed from a second material, for example a wear-resistant ceramic. The
diameter of
exit plate 7 is substantially smaller than the diameter of the opening 11 at
the steel end holder
3 shown in Figure 4 as a result of the tapering of the interior surface 14
from the steel end
holder 3 to the exit plate 7. The interior surface 39 that surrounds the
central bore 38 of exit
plate 7 is angled with respect to a central axis of the center bore 38. The
narrowest section of
the center bore 38 defines the narrowest portion of the passage through the
die body 18, and
thus sets the outer diameter of an extruded tube that is produced when a
billet 17 is pressed
through the die body 18. This diameter and the dimensions of the extruded
product created
using the die assembly 1 are discussed in more detail below with respect to
Figure 13.
[00561 Figure 9 shows the base plate 8, which couples the stacked plates that
form the die
body 18 to a rotational power source. For example, as shown in Figures 1 and
3, the base
plate 8 in the die assembly 1 couples the die body 18 to a spindle 56. The
spindle 56 is
driven to rotate by a motor that powers the rotation of the spindle 56 at a
set rotational speed.
The spindle 56 is connected to the base plate 8 by bolts which pass through
outer through-
holes 43 around the perimeter of the base plate 8 and transfer the rotational
force of the
spindle 56 to the base plate 8. The base plate 8 is also rotationally coupled
to the plates in the
die body 18 by bolts, such as bolt 2 shown in Figure 1, that pass through the
through-holes 12
of the die body 18 and into the holes 42 in the base plate 8.
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[0057] The base plate 8 includes a central bore 40 having an interior surface
41. The bore
40 and the interior surface 41 define an opening in the base plate 8 that may
have a wider
diameter than the diameter of the bore in the exit plate 7. The wider diameter
of the base
plate bore 40 allows the extruded material to exit the die body 18 without
directly contacting
.. the interior surface 41 and may allow for a cooling component, such as a
fluid source, to
partially enter the base plate 8 and apply a cooling fluid to extruded
material exiting the exit
plate 7 near the exit of the die body 18. The exit plate 7 may also include a
relief angle near
the back face of the plate that further facilitates the application of cooling
fluid, as discussed
below with respect to Figure 13.
[00581 The die assembly 1 is assembled prior to extrusion by stacking plates 3-
7 and
connecting the die body 18 formed by the plates to the base plate 8 with bolts
placed into the
through-holes 12 of the die body plates and into the holes 42 of the base
plate. The stacking
of these plates to form the die body 18 forms the interior profile of the die
body 18 that
causes extrusion of billets pressed through the die assembly 1. This inner
profile and the
orientation of the stacked plates are shown in the cross-sectional view of the
die assembly 1
in Figure 10.
[00591 The cross section in Figure 10 shows the die body 18 and the centering
insert 9
positioned for extrusion. The die plates 3-7 are coupled together and fastened
to the base
plate 8 by bolts 2 inserted into the series of through-holes 12 in the outer
perimeters 19, 25,
29, 32, and 36 of the plates. In this orientation, the opening 11 of the
interior passage 54 in
the die body 18 is aligned with the centering insert 9 to receive a billet
pressed through the
opening 15 of the centering insert 9 and into the die body 18 along the center
axis 45 of the
interior passage 54.
[00601 Each of the bore perimeters 23, 24, 28, 33, and 37 of the die plates 3-
7 abuts bore
perimeters in adjacent plates to form the tapered interior surface 14 that
outlines the interior
passage 54 through the die body 18. The inner surface 14 narrows the interior
passage 54
from the largest diameter of the passage at the opening 11 to the smallest
diameter at the exit
81, and the narrowing of the passage 54 causes the narrowing deformation and
extrusion of a
billet pressed into the rotating die body 18 during operation. The extrusion
requires friction
energy to be produced at the interface of the inner surface 14 to heat the
billet, and the energy
can create wear on the bore perimeters of the die plates 3-7. To reduce the
effect of the
friction wear and produce uniform stresses across the interior surface 14
during extrusion, the
inner surfaces 27, 31, 35, and 39 are designed to spread the friction
interface and reduce the
concentration of energy and friction on any one plate. The design of the inner
surfaces and
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the profile of the interior surface 14 may differ for different applications,
and in particular for
the extrusion of different materials. Depending on the material properties of
billets used for
extrusion, for example heat transfer properties that may affect the heating of
the billets during
extrusion, the inner profile of die plates in a die body may be varied to
spread work and wear
over the die plates. In addition, the die rotation speed may be varied to
increase the
efficiency of the die and avoid exceeding material properties of the billets.
For example, a
die rotation speed between about 200 rpm and about 1000 rpm may be used. In
certain
implementations, a slower rotation speed, for example about 300 rpm, may be
desired to
avoid applying a high level of torsional sheer to a billet while still heating
the billet to a
sufficient temperature for deformation. A faster speed, for example about 800
rpm, may be
used for a material that is not adversely affected by a higher torsional sheer
or that requires
more energy, and thus greater friction, to heat to a deformation temperature.
In other
implementations, die rotation speeds in excess of 100 rpm may be desired for
extrusion.
[00611 As shown in Figure 10, the inner surfaces 27, 31, 35, and 39 do not
taper at uniform
angles with respect to the central axis 45. Each surface in the depicted die
is tapered at an
angle that decreases from the entry plate 4 near the opening 11 to exit plate
7 at the exit 81.
This decreasing angle design may be desired for a particular extrusion
material or application
of the die assembly 1. In certain embodiments, however, the taper angle of the
interior
surface 27 with respect to the central axis 45 may be equal to or less than
the taper angle of
the adjacent surface 31. In the embodiment shown in Figure 10, the angle 46 at
which the
interior surface 27 of the entry plate 4 is tapered is greater than the angle
47 at which the
interior surface 39 of the exit plate 7 is tapered. The differences in taper
angles between the
plates spreads the frictional energy and stress over the plates as a result of
the differences in
diameters of the center bores from the opening 11 to the exit 81.
[0062] Each plate has an entrance diameter, for example diameter d5 of plate
4, and an exit
diameter, for example diameter d7 of plate 4. When a billet is pressed into
the plate, a
threshold amount of energy must be generated to heat and deform the billet
from the diameter
d5 to the diameter d7. This amount of energy is affected by the percent
reduction in
diameter, in particular the resulting percent reduction in cross-sectional
area of a billet as it
passes through the plate 4. If the central bores in plates 3-7 were each
tapered at a single
uniform angle, the diameter change from the entrance to the exit of each plate
would be
equal, and thus the percent reduction in billet cross-sectional area would
increase for each
successive plate. For example, if the absolute difference between diameters d5
and d7 of
plate 4 were equal to the absolute difference between diameters d6 and d8 of
plate 7, the
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percent reduction in the diameter of the central bore would be higher in plate
7 than plate 4,
and a greater amount of stress and energy could cause plate 7 to wear faster
than plate 4.
[0063] In addition to the percent area reduction of a billet over a plate,
mechanical and
thermal properties of the billet materials may dictate the number and design
of plates in a die
stack. For example, a billet material having high thermal conductivity may
heat up to a
deformable temperature more quickly than a material having a low thermal
conductivity, and
thus a shorter die with fewer plates may be used for the high conductivity
material. In
addition, the tapering angles of the inner surface of a die may be greater for
the high
conductivity material as a result of the quicker heating of the billet. In
other
implementations, dies of equal size having the same number of plates may be
used, and the
tapering angles of the dies may differ to accommodate the different thermal
properties and
heat the billets to a deformable temperature while spreading work and wear as
evenly as
possible over the die surface and the surface of a mandrel tip within the die.
[0064] A billet pressed through the die body 18 produces an extruded tube
product through
exit 81 of the die body 18 having an outer diameter that is similar to the
diameter d8, the
diameter at the narrowest portion of exit plate 7. The inner diameter of the
extruded product
is selected by advancing the mandrel bar 10 into the die body 18 with a
mandrel tip having an
end dimension, selected to create the inner diameter of the tube product, at
the end of the
mandrel bar 10. Figure 11 shows a mandrel tip 48 that may be coupled to the
end of the
mandrel bar 10 to create a desired inner diameter for extruded tubing. The
mandrel tip 48 has
an open end 82 that is configured to couple to the end of the mandrel bar 10.
The friction
energy and heat generated during extrusion may heat the mandrel tip 48, and
the open end 82
may receive cooling fluid, such as water or gas, from a cooling system that
runs through the
mandrel bar 10 to cool the mandrel tip 48.
[0065] Opposite the open end 82 of the mandrel tip 48 is a closed end 51. The
diameter of
the closed end 51 is the dimension that sets the inner diameter of a tube
extruded over the tip
48, and the tip 48 can be selected from a series of tips having different
diameters to achieve
extrusions with different inner diameter dimensions. Between the open end 82
and the closed
end 51 are three portions 49, 83, and 50 of the tip outer surface 84. During
extrusion, a billet
is pressed over the mandrel bar 10 and the tip 48 in the direction of arrow C
such that the
billet passes over a deformation region including tip portions 49 and 83, and
an end portion
50. When the tip 48 is positioned for extrusion, the tip is advanced into a
die until the closed
end 51 extends beyond the rear exit of the die at which the die diameter is
narrowest. A billet
having a hollow core diameter substantially equal to the outer diameter of the
tip portion 49 is
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then passed over the mandrel bar 10 and the tip 48. At the tip portion 49, the
diameter of the
surrounding die narrows, and friction between the die and the billet creates
energy that heats
the billet as the outer diameter of the billet is compressed. The heated
billet then passes over
the tip portion 83, and the inner diameter of the hollow core of the billet
decreases to the
outer diameter of end portion 50 as the material extrudes. This extrusion over
the mandrel tip
48 is discussed in more detail below with respect to Figures 12 and 13.
[0066] Figure 12 shows the die assembly 1 with the mandrel 10 and mandrel tip
48
advanced through the centering insert 9 and into the center passage 54 of the
die body 18.
The mandrel 10 is positioned such that the mandrel tip 48 extends through the
exit 81 in the
exit plate 7. As discussed above with respect to Figure 2, gripping elements
in an extrusion
press system may be used to hold the mandrel bar 10 and in the orientation
shown in Figure
12 and to resist rotation while the die body 18 is rotated and a billet passes
over the mandrel
bar 10.
[0067] Figure 13 shows the die assembly and mandrel tip configuration of
Figure 12 as the
billet 17 is passed through the die body 18 and extruded to form tubing 53.
During extrusion,
the die body 18 is rotated while the mandrel bar 10 and centering insert 9 are
held stationary.
The billet 17 is pressed into the die body 18 in the direction of arrow A and
contacts the
interior surface 14 of the die body 18 at a first contact point 85. The
interference contact
between the interior surface 14 and the billet 17 begins at the contact point
85 and generates
the energy that heats the billet 17 to a plastic deformable temperature.
[0068] As the billet 17 is advanced over the first portion 49 of the mandrel
tip 48, the taper
of the interior surface 14 applies a compression force to the outer surface of
the billet 17 that
presses the billet 17 inwards towards the mandrel tip 48. Because the billet
17 is in a plastic
deformation state, the material in the billet extrudes in the direction of
portion 83 of mandrel
tip 48 as the die body 18 decreases the outer diameter of the billet 17 from
the original
diameter d2. When the billet 17 reaches the tip portion 83, the taper of the
tip portion 83
towards the end portion 50 causes the inner diameter of the billet 17 to
extrude and decrease
from the original diameter dl as the billet advances further over the mandrel
tip 48. The
tapered surface of the mandrel tip 48 at the tip portion 83 may substantially
correspond to the
angle of the interior surface 14 in the area surrounding the tip portion 83 to
create
substantially uniform extrusion in that portion. For example, the outer and
inner diameters of
the billet 17 may decrease by substantially the same amount or by
substantially the same
percentage from the end of tip portion 83 proximate first tip portion 49 to
the end of tip
portion 83 proximate end portion 50.
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[0069] When the extruding billet 17 reaches the end portion 50, the inner
diameter of the
billet is reduced from the original diameter dl to the final diameter d3 of
the end tubing
product. As the billet 17 passes over the end portion 50, the outer diameter
of the billet 17
continues to decrease to the final outer diameter d4 when the extruded tubing
product 53 exits
the exit plate 7. At the point of exit, the formation of the extruded product
53 is complete.
Due to the friction and heating within the die body 18, the product 53 is at a
heightened
temperature upon exit from the die body 18, and a cooling element may be
applied to prevent
further deformation or increase operational safety of the extrusion press,
eliminate the escape
of extruded material, or maintain desired material characteristics. The bore
40 in the base
plate 8 is shown in Figure 13 with a diameter larger than the exit diameter of
the exit plate 7.
This configuration may be preferable in order to allow cooling elements and
cooling fluid to
reach into the base plate 8 and contact the extruded product 53 as soon as it
exits the final
bearing in the exit plate 7 for earlier cooling. The exit plate 7 includes an
angled relief
surface 86 to further facilitate the introduction of a fluid material as near
as possible to the
exit 81 of the die body 18. After the product 53 exits the base plate 8 and
passing through a
cooling system, the extrusion process is complete, and the product 53 may be
gathered for
post-processing.
[0070] It is to be understood that the foregoing description is merely
illustrative and is not
to be limited to the details given here in. While several embodiments have
been provided in
the present disclosure, it should be understood that the disclosed systems,
devices and
methods and their components may be embodied in many other specific forms
without
departing from the scope of this disclosure.
[0071] Various modifications will occur to those with skill in the art after
reviewing this
disclosure. The disclosed features may be implemented in any combination and
sub-
combinations, including multiple-dependent combinations and sub-combinations
with one or
more features described herein. The various features described or illustrated
above, including
any components thereof, may be combined or integrated into other systems,
Moreover,
certain features may be omitted or not implemented. Examples of changes,
substitutions and
alterations are ascertainable by one skilled in the art and can be made
without departing from
the scope of the information disclosed herein. All references cited herein are
incorporated by
reference in their entirety and made part of this application.
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