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Патент USA US2107846

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Feb. 8, 1938.
R. w. ATKINSON _
2.107.846
METAL EXTRUSION PRESS AND METHOD OF OPERATION
Filed Dec. 18, 1933
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INVENTOR
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ATTORNEYS
Feb. 8, 1938.
R. w. ATKINSON
2,107,846
METAL EXTRU’SION PRESS AND METHOD OF OPERATION
Filed Dec. 1a, 1953
.2 ShQetSLSheet 2
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Patented Feb. 8, 1938
2,107,846 }
UNITED STATES, PATENT OFFICE
2,107,846
EXTRUSION PRESS AND METHOD OF
OPERATION
Ralph W. Atkinson, Perth Amboy, N. J., assignor
to General Cable Corporation, New York, N. Y.,
a corporation of New Jersey
Application December 18, 1933, Serial No. ‘702,872
11 Claims. (Ci. 207-9)
This invention relates to metal extrusion presses
and the method of operating such presses. More
particularly the invention is concerned with
presses for extruding metal sheaths on electrical
5 cables. Ordinarily, cable sheaths are made of
lead or an alloy of lead. It is an object of this
invention to provide improved apparatus for ex
truding metal, and also to provide an improved
method of operating such apparatus in which the
10 metal to be extruded is not exposed to air or
other gases. Other objects and advantages of
the invention will appear hereinafter.
The invention will be best understood from the
following description when read in the light of
15 the accompanying drawings illustrating a certain
speci?c embodiment of the invention.
>
In the drawings:
Fig. l is an elevation of a press for extruding
cable sheaths and of the container for supplying
a‘; molten metal to the press;
'
Fig. 2 is a top plan view to enlarged scale of
the stuf?ng box which connects the upper end
of the press cylinder and‘ the press ram;
Fig. 3 is a vertical section through the stuffing
box substantially on the line 3--3 of Fig. 2;.
Fig. 4 is a vertical section through the stuffing
box substantially on the line 4-4 of Fig. 2; and
Fig. 5 is a section through one of the openings
in the stu?ing box Wall substantially on the line
30 5-5 of Fig. l, but to the same scale as Figs. 2
to 4.
In sheathing electrical cables with metal there
are two types of vertical presses in general use.
In one of these the press cylinder is stationary
and the press rarn moves, while in the other the
press ram is stationary and the pressicylinder
moves. The present invention may be used with
both types of presses, but merely for convenience
it is illustrated herein with reference to a press in
m which the cylinder is stationary.
The actual extrusion of metal is not continu
ous in either type of press for the reason that
it is necessary to separate the ram and the cylin
der and recharge the cylinder with metal when a
majority of the original charge of metal has been
3.4
extruded from the cylinder. In recharging, the
cylinder is ?lled with molten metal, and then it
is necessary to wait until the metal cools suffi
ciently to solidify before the extrusion operation
5,“ can be continued.
Heretofore it has been the common practice in
charging a press cylinder to separate the cylinder
and the ram, and then to ?ll the cylinder with
molten metal from a nearby melting pot by
55 opening a valve at the bottom of the pot and
permitting metal to flow down an inclined
trough, the lower end of which has been moved
over the open end of the press cylinder. When
the cylinder has been ?lled with molten metal
the valve at the bottom of the pot is closed, and 5
an effort is made to remove the dross on the top
surface of the metal in the cylinder either by
flotation or by skimming.
The ram is moved
downwardly to seal the charge and then it is
necessary to suspend operations until the molten 10
metal in the press cylinder has solidi?ed. After
solidi?cation of the charge the extrusion oper
ation may be continued.
in operating presses as described above, im
purities are accumulated by or formed in the 15
molten metal, and also on the exposed surface of
the hot metal slug remaining in the cylinder, and
on the thin layers of hot metal on the surfaces
of the ‘cylinder and ram.
Exposure of the molten
metal to the air as it issues from the melting pot 2G
and ?ows through the trough to the press cylin
der is accompanied by oxidation of the metal.
This oxidation results in the formation of dross
which is carried into the press cylinder. The
upper surface of the slug left in the cylinder at 25
the completion of an extrusion operation also
begins to oxidize as soon as the ram leaves it on
its up-travel. Likewise the thin ?lm of metal
on the inner surface of the cylinder and the end
of the ram oxidizes and ?nds its way into the 30
charge. This oxidized ?lm tends to prevent per
fect welding of the new charge, and while a por
tion of the oxide may ?oat to the top and be
skimmed off, a part of it ‘will remain in the
charge. This oxide may reduce the strength of 35
the bond in the cable sheath. Furthermore,
some metal may cling to the trough at the com—
pletion of a charging operation. Such metal
will oxidize in the air and build up into large
particle sizes which will be carried, possibly with 40
other dirt, into the cylinder with the molten
metal during the next charging operation.
In charging a press in the manner just de
scribed the metal which runs into the cylinder
strikes the relatively cold wall of the cylinder 45
and freezes in an irregular lump. The surface
of this lump ?lms over instantly and is continu
ously spattered with more hot metal, forming a
larger lump containing oxide and gas bubbles
which eventually must appear in the cable 50
sheath. These entrapped air or gas pockets are
compressed to very small size during the extru
sion operation, and expand again after passing
out of the die.
If the pocket is near the surface
of the sheath it will explode outwardly and per- 55
2,107,846
haps may be discovered and repaired, but it is
just as likely that the pocket will occur adjacent
the inner surface of the sheath and burst in
wardly, to the detriment of the cable insulation,
as well as the sheath. These pockets weaken
the sheath mechanically, even if they do not
gas~
burst.
preferably has a sliding ?t with the press ram cu
225. This opening 46 is enlarged near the outer
surface of the stuihng box to receive a packing
According to the present invention a commer
cially practicable method and apparatus is pro
vided for extruding cable sheaths, in which oxida
tion of the slug remaining in the cylinder prior
ring All, for example asbestos, which may be com
pressed by means of the pacln'ng gland 48 and
the screws 49 securing the packing gland to the in
stu?lng box 21'. For convenience in assembling,
to a charging operation is prevented, and in which
molten metal passes from the melting pot or
other container to the press cylinder without ex
posure to the air or any other gas at any point
during its movement. Fw‘thermore, the inner
surfaces of the cylinder and lower end of the
ram, both of which come in contact with the
metal,
areare
therefore
not exposed
free from
to the
oxides.
air or other
R ferring first to
1, extending upwardly
‘cm the base 23 are the vertical columns 2i, four
3.. number, which support near their upper ends
press canopy
r .c.
comprising the hydraulic
Vertically movable within the cyl
r .3 is the hydraulic piston 24. Secured on
lower e -d of the hydraulic piston
as by
cans of the SClL‘WS 25', is the downwardly ex
te
30
packing 43, for example asbestos, insures
tight connection between the press cylinder and
the stufhng box.
The opening 46 in the top of the stuf?ng box
‘ g press ram ‘26.
The press ram
passes
downwar‘ly through the stuii?ng box 2?, to be
described more fully hereinafter, into the upper
end of the press cylinder 33.
The press cylinder 23 is secured on top of the
die block 25, having a horizontal die opening 33
" rough which the cable passes during the sheath
ilovement
ng operation.
or" the
The
press
die blocir
ram into
rests and
on the
outbase
of the
ress cylinder for the purpose of extruding metal
(-A. herefrom is accomplished by means of the hy
draulic cylinder and piston in the usual manner.
Surrounding the press ram 26 and secured to
the upper end of the press cylinder 33, as by
means of the screws 32 is the stumng box 2?.
the packing gland may be made in two pieces, as
shown in Fig. 2, and when it is forced downwardly
by means of the screws 49 the packing ring ill
will be pressed against the surface of the rain '18,
forming a seal to prevent passage of air or other
gas into the press cylinder between the press ram
and the stuffing box.
As may be seen in Figs. 3 and 4», the lower edge
of that portion of the stuiilng box having a slid~
ing ?t with the press ram preferably is in the
form of a scraping edge 56. As the ram is with
drawn from the cylinder at the conclusion of an
extruding operation this edge will scrape from
the stuiface of the ram any metal which may
have escaped past the end of the ram during the
extruding operation.
The metal so removed from the ram will col~
lect within the stu?ing box 21, and preferably
means are provided for melting this metal so llll
that it may return to the press cylinder while
the cylinder is being charged with molten metal.
This heating means conveniently may take the
form of an electrical heating unit 53 located with
in the stuf?ng box, and preferably separated from '
the lower inner wall of the stuf?ng box by space
or by thermal insulation so as to minimize the
heat lost by the unit 53 by conduction. Ordi
narily the amount of metal escaping past the
end of the ram during an extruding operation is 40
small, and it will not be necessary to melt the
metal accumulated within the stui?ng box each
time that the press cylinder is charged with
Connected in an opening through the wall of the molten metal.
stuffing box is a pipe 33 through which the press
The connection of the pipe 33 to the stui?ng
cylinder is charged with molten metal. The pipe ‘ box is shown in Fig. 3. It will be apparent that
conveniently is connected, as by means of pipe molten metal entering the stu?ing box through
flanges and the pipe 34, with the outlet pipe 35 the pipe 33 will continue down the inclined chute
of a container 38 for molten metal, for example 56 formed in the inner surface of the stuf?ng'box
50 the melting pot. Conveniently an expansion
and be discharged into the press cylinder 28.
joint, (not shown) may be included in this pipe During the charging operation the press ram 26
connection. Flow of molten metal from the con
is Withdrawn from the press cylinder as shown in
tainer 33 through the pipes 35, 34 and 33 to the broken lines in Fig. 3.
press cylinder 23 conveniently may be controlled
Throughout the charging and extruding oper
by means of a valve, (not shown) located within ations the press cylinder and the stuf?ng box
the container 36 and operated by the valve stem desirably are evacuated. Connecting with the
3'! extending upwardly through the top of the interior of the stuffing box through an opening in
container 36. The pipes 33, 34 and 35 may be the wall thereof is a pipe 58 connected, for ex
covered with heat insulating material if desired. ample through a valve H, to a vacuum pump,
60
The construction of the stuffing box 21 is shown indicated diagrammatically at 12. Desirably, a
more clearly in Figs. 2 to 5 inclusive. Conven
very high vacuum is maintained so that the in
iently the stui?ng box is formed in two pieces 38 terior of the press cylinder and the stuffing box
and 39 which are connected together in posi— are substantially free from air and other gases
tion about the press ram by means of the screws which might cause dross to form, or which might
43 passing through openings in the outwardly be included in the molten metal in the form of
extending ?anges H. A gas-tight connection gas pockets.
between the two parts of the stu?ing box is ob
Conveniently means are provided for observing
tained by means of the gaskets 42, for example the level of the molten metal as it nears the top
asbestos, compressed between the ?anged edges of the press cylinder during a charging operation.
4i.
As shown in the illustrative embodiment such
Between the upper end of the press cylinder means may take the form of oppositely disposed
28 and the lower edge of the stu?ing box 2‘! is a. windows BI and 62.
packing ring 43, which is compressed as the vscrews
The cross section through one of the windows
32 are turned down to secure the stu?ing box in shown in Fig. 5 illustrates the construction more
position on the upper end of the cylinder. The fully. The window opening in the wall of the
3
2,107,846
. stu?ing box is provided with a removable rim 64 ~. extrusion, with the harmful consequences set
held in place by means of screws 65 and the wing
nuts 66. Mounted in the rim 64 is a thick pane
01' glass 61, conveniently held therein along with
the gasket $8 by means of the ring 69 secured
to the rim M with screws ‘ill. ,As the ring 64 is
III
tightened in place by screwing down the wing
forth hereinabove. In the case of steam, how
ever, the compression within the cylinder will
produce a liquid, with a vast reduction in volume,
and expansion to gaseous form is prevented by a
relative moderate pressure even at ‘the temper
ature of the lead as it is being extruded. The
nuts 8% the gasket 68 provides a gas-tight seal
between the stuffing box 2'? and the glass 61.
.10
The operation of the extruding apparatus will
now be described. Upon the completion of an
extruding operation the press ram 26 is with
comparatively small volume of the space in which
the liquid will be found will result in the lead
surrounding it having su?icient strength to main 10
tain the liquid in its original volume without ex»
pansion to vapor form, even at the extruding
drawn upwardly from the press cylinder 28 until
the lower end of the ram is completely clear of
the cylinder as shown in broken lines in Fig. 3.
As the ram is withdrawn from the cylinder any
metal which may have escaped past the end of
the ram during the preceding extruding opera
tion, is scraped from the wall of the ram by the
scraping edge 56, and collects inside of the
stui?ng box 2?, without injury to the packing
ring 4i".
7
' .
The valve controlling the flow of molten metal
from the container 35 through the pipes 35, 3d
and 33 is then opened to permit molten metal to
flow from the container 36 into the press cylin
_ der.
If the amount of metal scraped from the
wall of the ram and collected within the stu?ing
box is su?iciently great the electrical heating
units 53 may be operated to melt this metal so
that it will flow down the inclined inner wall of
the stu?ing box into the press cylinder.
As the level of metal in the press cylinder ap
proaches the top of the cylinder it may be ob
served through the windows 6! and B2, and when
the metal reaches the desired level the valve may
be closed to stop further ?ow. The charge may
then be sealed, and when it has solidi?ed the
metal may be extruded by downward movement
40 of the press ram.
Throughout the charging and extruding oper
ations the space within the stu?ing box 2'I_ and
within the press cylinder desirably is evacuated
through the pipe connection‘ 58. No air or other
gases are present, or come in contact with the
metal from the time the molten metal leaves the
container 36 until the solidi?ed metal is extruded
from the opening 30 in the die block 29. Conse
quently there can be no oxidation or other dross
50 formation in the metal, and the formation of gas
pockets or bubbles in the press cylinder is pre
vented.
‘
.
Instead of maintaining a high vacuum in the
space within the stu?ing box and the press cyl
in .qt inder during the charging operation it maybe
desirable in some cases to introduce into this
space steam or some liquid which is inert chem
ically with respect to the metal being extruded,
and which is a vapor at the temperature of the
press cylinder and at atmospheric pressure, but
which may be lique?ed at the melting point of
the extruded metal. Conveniently, the steam or
other inert material may be‘ supplied to the press
cylinder through the pipe 58, connected, for ex—
ample through a valve 13, with a source of the
inert material indicated diagrammatically at ‘I4.
Steam not only is inert chemically with respect
to lead, but steam is a vapor at the temperature
of the cylinder and atmospheric pressure, and
70 yet is lique?ed by a reasonable pressure at any
temperature that is reached by the cable sheath.
If a bubble of permanent gas or very low boiling
liquid be compressed within the mass of the lead
during the extruding operation the bubble may
75 expand substantially to its original volume after
temperature.
'
Applicant has provided improved apparatus
whereby metal sheaths may be extruded about
electrical cables, and in which oxidation of the
metal during the extruding operation is pre
vented. Furthermore, introduction of impurities
and formation of gas pockets in the metal dining
the press charging operation is prevented.
It will be understood that the present inven
tion may be variously modi?ed and embodied
within the scope of the subjoined claims.
I claim:
1. In apparatus for extruding metal sheaths on
electrical cables the combination of a cylinder, a
die block having an opening for the passage of a
cable therethrou'gh connected to one end of said
cylinder, 9. ram extending into the other end of
said cylinder, means for causing relative move 30
ment between the cylinder and the ram, sealing
means connecting the cylinder and the ram pre
venting the entrance of air into the cylinder
around the ram while permitting relative move
ment therebetween, and means for removing sub 35
stantially all air and other gases from the space
between the cylinder and the ram under the said
sealing means.
\ 2. In apparatus for extruding metal sheaths on
electrical cables the combination of a cylinder, a 40
die block having an opening for the passage of a
cable therethrough connected to one end of said
cylinder, a ram extending into the other end of
said cylinder, means for causing relative move
ment between the cylinder and the ram, sealing 45
means connecting the cylinder and the ram pre
venting the entrance of air into the cylinder
around the ram while permitting relative move
ment therebetween, and an acute angled scraping
edge closely encircling the ram below the sealing 50
means for removing any metal which may have
been forced out between the cylinder wall and the
head of the ram during an extruding operation
from the surface of the ram and for directing
the metal away from the ram as the latter is I
withdrawn from the cylinder.
3. In apparatus for extruding metal sheaths
on electrical cables the combination of a cylinder,
2. die block having an opening for the passage of
a cable therethrough connected to one end of A
said cylinder, 9. ram extending into the other end
of said cylinder, means for causing relative move
'
ment between the cylinder and the ram, sealing
means connecting the cylinder and the ram pre
venting the entrance of air into the cylinder
around ‘the ram while permitting relative move
ment therebetween, a scraping edge closely en
circling the ram below the sealing means, for
removing any metal which may have been forced.
out between the cylinder wall and the head of the
ram during an extruding operation from the sur
face of the ram as the latter is withdrawn from
the cylinder, and means for melting any such
metal and causing it to return to the cylinder
during a charging operation.
75
4
2,107,846
4. In apparatus for extruding metal sheaths on
electrical cables the combination of a cylinder,
a die block having an opening for the passage of
a cable therethrough connected to‘one end of said
In cylinder, 2. ram extending into the other end of
said cylinder, means for causing relative move
ment between the cylinder and the ram, means
for charging the cylinder with molten metal, and
means for removing substantially all air and
10 other gases from the cylinder during a charging
operation.
'
5. In apparatus for extruding metal sheaths on
electrical cables the combination of a cylinder, 9.
die block having an opening for the passage of
a cable therethrough connected to one end of
said cylinder, a ram extending into the other end
of said cylinder, means for causing relative move
ment between the cylinder and the ram, means
for charging the cylinder with molten metal, and
means for supplying steam to the cylinder during
a charging operation.
6. The method of operating apparatus for ex
truding metal sheaths on electrical cables, com
prising a cylinder, die block and ram, which
method comprises charging the cylinder with
molten metal free from impurities, permitting
the molten metal to cool and solidify, preventing
access of air to the molten metal during the
charging and cooling operations, removing from
30 the cylinder during the charging operation any
gas which may have been entrained in the molten
35
metal, and effecting relative movement between
the cylinder and the ram to extrude the solidi?ed
metal through the die block.
cylinder, and means for charging the cylinder
with fused material through the wall of the re
ceptacle.
9. In apparatus for extruding metal sheaths on
electrical cables the combination of a cylinder, a
die block having an opening for the passage of a
cable therethrough connected to one end of said
cylinder, a ram extending into the other end of
said cylinder, means for causing relative move
ment between the cylinder and the ram, an annu 10
lar casing surrounding the ram and connected
?uid tight to the end of the cylinder, a packing
secured in the wall of the annular casing encir
cling the ram and preventing entrance of air into
the cylinder around the ram while permitting 15
relative movement therebetween, and means con
nected to said annular casing for removing sub
stantially all air and other gases from the space
between the cylinder and the ram and under the
annular casing.
/
10. In apparatus for extruding metal sheaths
on electrical cables the combination of a cylinder.
a die block having an opening for the passage of
a cable therethrough connected to one end of said
cylinder, a ram extending into the other end of
said cylinder, means for causing relative move
ment between the cylinder and the ram, sealing
means connecting the cylinder and the ram pre
venting the entrance of air into the cylinder
around the ram while permitting relative move- I
ment therebetween, and an acute angled scraper
between said sealing means and the head of the
ram for removing any metal which may have been
forced out between the cylinder wall and the head
7. The method of operating apparatus for ex
of the ram during an extruding operation from the
truding metal sheaths on electrical cables com
prising a cylinder, die block and ram, which
surface of the ram and for directing the metal
method comprises charging the cylinder with
molten metal free from impurities, permitting
40 the molten metal to cool and solidify, preventing
from the cylinder.
11. In apparatus for extruding metal sheaths
access of air to the molten metal during the
charging operation by maintaining a blanket of
steam over the metal in the cylinder, and eil’ect
ing relative movement between the cylinder and
the rain to extrude the solidi?ed metal through
the die block.
8. In an apparatus for charging an extrusion
press cylinder having a cooperating ram nor—
mally retirable from the cylinder to permit
charging of the same through the ram entrance
aperture thereof, a receptacle normally empty of
fused material supported upon the cylinder and
having an aperture in the bottom thereof pro
vided with a beveled edge for providing an en
trance into the cylinder and aligned with the
ram entrance aperture of the cylinder, said re
ceptacle constituting a seal between the cylinder
and the rain to exclude the atmosphere from the
away from the ram as the latter is withdrawn
on electrical cables the combination of a cylinder,
a die block having an opening for the passage 0!
a cable therethrough connected to one end of said
cylinder, a ram extending into the other end of
said cylinder, means for causing relative move
ment between the cylinder and the ram, sealing 45
means connecting the cylinder and the ram pre
venting the entrance of air into the cylinder
around the ram while permitting relative move
ment therebetween, means be‘ween said sealing
means and the head of the ram for removing any
metal which may have been forced out between
the cylinder wall and the head of the ram during
an extruding operation from the surface of the
ram as the latter is withdrawn from the cylinder,
and an electrical heating element for melting any
such metal and causing it to return to the cylinder
during a charging operation.
RALPH W. ‘ATKINSON.
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