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Патент USA US2135194

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Nov. 1, 1938.
w. s. UNDERHILL
Filed June 21, 1935
2,135,194
2,135,194
Patented Nov. 1, 1938
UNITED STATES
PATENT OFFICE
2,185,194
EXTRUSION OF TUBULAR SHAPES OF ALU
MINUM AND ALLOYS THEREOF
Wyvel 8. Under-hill, Detroit, Mich, assignm- to
Aluminum Company of America, Pittsburgh,
Pa., a corporation of Pennsylvania
Application June 21, 1935, Serial No. 27,84;
comm. (Cl. 207-17)
This invention relates to the formation of through which the metal flows to the space or
‘ tubular shapes of aluminum and of aluminum
alloys by extrusion, and its chief object is to
provide an improved method and apparatus by
s which tubular articles or shapes can be extruded
at high speed with accurately ?nished inner
and outer surfaces and without unwanted varia
tions or irregularities in wall thickness. Here
tofore the common practice has been to form the
10 longitudinal hollow or bore by means of a “?oat
ing" mandrel or core. In that method a pierced
billet is used, that is, one provided with a longi
tudinal bore, and the mandrel, in the form of a
rod with a slight taper, is mounted loosely on
15 the piston or plunger and extends into the bore
of the billet, which bore is aligned with the die
at the forward end of the cylinder so that the
end of the mandrel extends into the die. Then
as the piston advances, the metal is forced out
20 through the annular space between the wall of
the die opening and the surface of the mandrel,
which extends through the die opening and ad
vances at the same rate as the forward move
ment of the piston. It is assumed that with the
25 billet ?tted closely to the cylinder and the bore
accurately aligned with the die opening, the
radial pressures exerted by the metal upon the
?oating mandrel will be equal in all directions,
thereby keeping the mandrel accurately posi
30 tioned in the die opening at all times. In prac
tice, however, this condition of equal pressures
is rarely, if ever, obtained, with the result that
the mandrel shifts radially of the cylinder as it
advances, thus producing variations in the wall
35 thickness of the article. To avoid the defect
of variation in wall thickness incident to the use
of a ?oating mandrel it has been proposed to
mount the mandrel or core rigidly by means of
a longitudinal fin terminating short of the die
40 opening itself but permitting the core to extend
chamber in which the streams expand and coa
lesce or weld together, should have a forward
spread or ?are, and their rear ori?ces, through
which the metal enters the passages, should have 5
shearing edges, so that the metal is formed into
streams in part, at least, by a shearing action
rather than wholly by a molding or compressing
action. The welding space or chamber, between
the die opening and the adapter passages, should in
not taper forwardly, as if to progressively crowd
the metal radially inward toward the core and
the die opening. Preferably the chamber has
a pronounced forward ?are. The ori?ce of the
die opening, through which ori?ce the metal en- 15
ters the die opening, should have a shearing edge,
and the core should also have a circumferential
shearing edge, located substantially in the same
plane as the shearing edge of the die opening,
so that the metal will be sheared, at least in part. 20
into space between the core and the wall of the
die opening. Beyond these shearing edges the
metal should, in general, have quick relief, that
is, it should pass promptly out of contact with
the die surfaces.
25
Referring now to the accompanying drawing,
in which I have shown a form of the invention
designed to produce a cylindrical pipe:
Fig. l is a longitudinal section showing the
extrusion cylinder and plunger, and a die struc- 30
ture embodying my invention in convenient and
efficient form.
Fig. 2 is an end view of the “adapter", from the
right of Fig. 1.
Fig. 3 is a cross section of the adapter, on the 35
the metal is divided by the core supporting an as
it ?ows toward the die opening the two edges will
unite in the space around the core immediately
line 3—3 of Fig. 1.
Fig. 4 is a longitudinal section on the line 4-4
of Fig. 2.
The extrusion cylinder and the plunger are
shown, somewhat diagrammatically, at Ill and ll, 40
respectively. In the embodiment illustrated the
die structure is composed of two parts, one,
marked i2, I call the adapter. The other is a
die plate l3. The adapter is cylindrical in form,
45 back of the die opening, after which the metal
will be forced through the annular space between
the wall of the die opening and the surface of
?tted tightly to the forward or exit end of the 45
extrusion cylinder, and carries the mandrel or
core II by means of four radial fins or supports
into the die opening; the idea being that although
the core.
i5, symmetrically arranged and providing be
In the course of my experience with cores rigid
50 ly supported in the adapter I have found that for
tween them four passages, l6, through which
metal ?ows forwardly under the pressure of the 50
ease of working, uniformly high quality of prod
ucts, and extrusion at speeds comparable to those
obtainable with a ?oating mandrel, the die struc
ture should have certain features, as follows:
55 The passage or passages, preferably two or more,
The adapter is preferably made of a single
piece, as it is dii‘licult to obtain adequate strength
in a built up device. The passages i6 through
which the metal ?ows to the die ?are forwardly 5s
plunger.
2
>
'
_,
8,180,194
and their entrance orifices are formed with
shearing edges If. These edges are preferably
sharp, but a slight rounding or chamber is per
missible to lessen chipping or wear. Or the face
of the adapter may be slightly dished around the
passages.
It is desirable that as the billet (not shown)
is advanced to shear the metal into the passages
iii, the metal which is actually in contact with
the rear face of the die structure does not move
on such face but that the radial ?ow of the metal
toward the passage takes place in rear of the
billet face. That is to say, for the best results
the ?ow should be wholly inside of the billet. For
15 this reason any forward coning or tapering of the
rear face of the die structure toward the passages
l8 should be insumclent to permit any such slip
page or movement, and I therefore prefer to make
the rear face of the die structure ?at or substan
20 tially so and at right angles to the axis of the
cylinder.
At their forward ends the passages I8 open into
an annular space or chamber l8 (around the free
or unsupported forward portion of the core II)
25 in which the metal streams coalesce or weld to—
gether. This chamber is preferably formed with
a forward ?are toward its front wall, which in
the present instance is the rear face of the die
plate l3. The latter is fitted tightly to the front
30 of the adapter and centered thereon in any con
venient way, as by means of a rib and groove as
indicated at i9. \By preference the front wall of
the chamber is substantially ?at and at right
angles to the die.
85
The die plate i3 is provided with a die-opening,
into which the free or unsupported end of the
wallofthechamber ll theadvancingrodsare
arrested and thereafter expand in the chamber
and in the feed
es as more and more metal
is fed into the latter by the pressure of the plum:
er. When the feed
es and welding cham
ber are full the continued pressure of the plunger
shears the metal into tubular form at the die
shearing edges II, 28. As the operation proceeds
the billet advances as a whole and the passages Ii
and welding chamber II are kept full. As the 10
billet advances, its curved surface slides over the
inner curved surface of the cylinder, but at the
rear face of the die structure there appears to be
no slip or movement of the metal which is in con
tact with the rear face of the die structure.
on 16
the contrary, the radial ?ow of the metal (in
wardly from the longitudinal surface and out
wardly from the axis of the billet) toward the
ori?ces of the passages l6 takes place in rear of
the forward face of the billet, that is to say, inside
of the billet. The same is true of the metal in
the welding chamber, with respect to the front
face of the latter.
It is to be understood that the invention is not
limited to the embodiment herein speci?cally ll
lustrated and described but can be embodied in
other forms without departure from its spirit as
de?ned by the appended claims. Nor is the in
vention limited to the extrusion of shapes of cir
cular cross section, inside or outside or both,
but can be employed in forming other shapes,
regular and irregular.
I claim:
'
1. Method of extruding tubular shapes of alu
minum and alloys thereof, comprising pressing a
billet of aluminum or an alloy thereof against a
mandrel or core ll extends to form the annular surface having one or more shearing-edged open
space through which metal passes from the weld
ings to form thereby one or more streams of
ing chamber l8. At the rear face of the die plate ' metal; continuing the pressure on the billet and
the opening is formed with a narrow (l. e., axially thereby delivering the streams into a welding
short) flange 20 providing a rear shearing edge space and against a surface having an annular
2|. Beyond the ?ange the opening in the die
plate ?ares slightly in the forward direction, as
indicated in Fig. 1.
The forward end of the core I l is formed with
a circumferential ?ange 22, providing a rear
shearing edge 23 preferably in the plane of the
shearing edge 2! around the opening in the die
plate I3.
The two ?anges should be narrow, in
general no thicker than enough to give any nec
essary or desired smoothing effect on the inner
and outer surfaces of the tubular article. If the
flange 20 is omitted the inner surface in front of
the shearing edge 2| may be parallel to the axis
of the die for an equivalent distance.
It is in
general important that after being shaped by the
shearing edges, and any necessary or desired
smoothing by the die surfaces beyond these edges,
the metal have immediate relief, that is, pass out
of contact with the die. For a pipe having an
inside diameter of an inch and three-eighths and
a wall thickness of about a quarter of an inch,
a ?ange thickness (measured axially) of about an
eighth of an inch is satisfactory. In general the
65 axial thickness need not exceed about one tenth
of the inner diameter of the tubular article and
in the case of large pipe it can often be much less.
I have not indicated any means for holding the
die structure parts together or the whole in place
70 at the end of the cylinder, as any suitable means
may be employed for the purpose, preferably such
as will permit easy detachment.
In operation, the ?rst effect of the advancing
plunger is to form rods of metal at the shearing
75 edges ll of the passages I5. Meeting the front
opening formed by inner and outer shearing
edges; and continuing the pressure to force the
metal from the welding space out through the
said annular opening and thereby form a tubular
shape.
2. Method of extruding tubular shapes of alu
mlnum and alloys thereof, comprising applying
pressure upon a billet of the metal to cause the
same to flow under the in?uence of the applied
pressure, providing shearing means disposed sub
stantially normal to the direction of ?ow of the
metal to form one or more streams of the metal,
arresting the forward progress of the stream or
streams to expand and coalesce the metal, and
continuing the pressure to force the coalesced
metal through an aperture defined between exte
rior and interior shearing means, whereby a tu
bular shape is formed.
3. Method of extruding tubular shapes of alu
minum and alloys thereof, comprising pressing a
billet of aluminum or an alloy thereof against a
substantially ?at surface having one or more
shearing-edged apertures to form thereby one or
more streams of metal; continuing the pressure
on the billet and thereby delivering the streams
into a coalescing and welding chamber and
against a surface having an opening formed by
inner and outer shearing edges; and continuing
the pressure to force the metal from the welding
space out through the said opening to thereby 70
form a tubular shape.
4. Method of extruding aluminum and alloys
thereof, comprising pressing a billet of the metal
against a substantially ?at surface having one or
3
2,135,194
more forwardly extending, forwardly ?aring pas
edged openlng in the substantially ?at surface
sages to form thereby one or more streams of
of the welding chamber and a core extending into
said opening and having a shearing edge lying in
the plane of substantially ?at surface of the weld
ing chamber, whereby a tubular shape is formed.
6. An extrusion-die structure comprising, in
combination, an adapter element, and a die plate;
said adapter element having a substantially ?at
metal, continuing the pressure on the billet and
thereby delivering the stream or streams into a
welding and coalescing space, arresting the ?ow
of the stream or streams to completely ?ll the
passages and welding space, and continuing the
pressure to force the metal from the welding space
out through an aperture de?ned between an
10 opening in a. surface enclosing the welding space
and a core member extending into said opening,
whereby a tubular shape is formed.
5. Method of extruding aluminum and alloys
thereof, comprising pressing a billet against a
15 substantially ?at surface provided with one or
more forwardly extending, forwardly ?aring pas
sages leading therefrom and terminating in a
rear face and one or more forwardly flaring pas
sages extending forwardly through the adapter 10
and terminating in an expansion chamber, and a
core secured to said adapter and extending into
the expansion chamber, said core having a cir
cumferential ?ange at its unsupported extremity;
the die plate having a substantially flat rear face 15
in abutting relationship with the adapter, said
rear face forming a wall of the expansion cham
welding chamber to form thereby one or more
ber, and a die aperture in the die plate into
streams of metal, continuing the pressure and
20 thereby delivering the stream or streams against
a substantially ?at surface forming a wall of the
welding chamber to arrest forward movement of
the stream or streams and thereby completely
flll the passages and welding chamber with metal,
25 and continuing the pressure on the billet to force
the metal from the welding chamber through an
annular aperture de?ned between a shearing
which the aforementioned core extends, said core
and die aperture cooperating to de?ne therebe
tween an axially short passage having parallel
walls; said adapter element and die plate being
provided with aligning means which permit sep
aration of the adapter and die plate irrespective
of unextruded metal Within the adapter follow 25
ing an extrusion operation.
WYVEL S. UNDERHILL.
CERTIFICATE OF CORRECTION .
Patent No . 2,15 5,1914,
November 1 , 1958 ,
WYV'EL S. UNDERHILL.
It is hereby certified that error appears in the print ad specification
of‘ the above numbered patent requiring correction as follows: Page 2, first
‘column, line 5, for the word "chamber" read chamf‘er; and that the said
Letters Patent shouldbe read with this correction therein that the same
may conform to the record of the case in the Patent Office.
Signed and sealed this 27th day of December, A. D. 1958.
Henry’ Van Arsdale
(Seal)
Acting Commissioner of Patents,
3
2,135,194
more forwardly extending, forwardly ?aring pas
edged openlng in the substantially ?at surface
sages to form thereby one or more streams of
of the welding chamber and a core extending into
said opening and having a shearing edge lying in
the plane of substantially ?at surface of the weld
ing chamber, whereby a tubular shape is formed.
6. An extrusion-die structure comprising, in
combination, an adapter element, and a die plate;
said adapter element having a substantially ?at
metal, continuing the pressure on the billet and
thereby delivering the stream or streams into a
welding and coalescing space, arresting the ?ow
of the stream or streams to completely ?ll the
passages and welding space, and continuing the
pressure to force the metal from the welding space
out through an aperture de?ned between an
10 opening in a. surface enclosing the welding space
and a core member extending into said opening,
whereby a tubular shape is formed.
5. Method of extruding aluminum and alloys
thereof, comprising pressing a billet against a
15 substantially ?at surface provided with one or
more forwardly extending, forwardly ?aring pas
sages leading therefrom and terminating in a
rear face and one or more forwardly flaring pas
sages extending forwardly through the adapter 10
and terminating in an expansion chamber, and a
core secured to said adapter and extending into
the expansion chamber, said core having a cir
cumferential ?ange at its unsupported extremity;
the die plate having a substantially flat rear face 15
in abutting relationship with the adapter, said
rear face forming a wall of the expansion cham
welding chamber to form thereby one or more
ber, and a die aperture in the die plate into
streams of metal, continuing the pressure and
20 thereby delivering the stream or streams against
a substantially ?at surface forming a wall of the
welding chamber to arrest forward movement of
the stream or streams and thereby completely
flll the passages and welding chamber with metal,
25 and continuing the pressure on the billet to force
the metal from the welding chamber through an
annular aperture de?ned between a shearing
which the aforementioned core extends, said core
and die aperture cooperating to de?ne therebe
tween an axially short passage having parallel
walls; said adapter element and die plate being
provided with aligning means which permit sep
aration of the adapter and die plate irrespective
of unextruded metal Within the adapter follow 25
ing an extrusion operation.
WYVEL S. UNDERHILL.
CERTIFICATE OF CORRECTION .
Patent No . 2,15 5,1914,
November 1 , 1958 ,
WYV'EL S. UNDERHILL.
It is hereby certified that error appears in the print ad specification
of‘ the above numbered patent requiring correction as follows: Page 2, first
‘column, line 5, for the word "chamber" read chamf‘er; and that the said
Letters Patent shouldbe read with this correction therein that the same
may conform to the record of the case in the Patent Office.
Signed and sealed this 27th day of December, A. D. 1958.
Henry’ Van Arsdale
(Seal)
Acting Commissioner of Patents,
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