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Патент USA US2104906

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Jan. 11, 1938.
H. MUELLER ET AL
2,104,906
MEANS FOR CASTING ROLLS
Filed April 6, 1935
2 Sheets-Sheet l
WITNESSES
ATTORNEYS.
Jan. 11, 1938. I
H. MUELLER Er AL
I
2,104,906
MEANS FOR CASTING‘ ROLLS
Filed April 6, 195-5
r’ /
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2 Sheets-Sheet 2
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FIG. ‘30
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INVENTORY
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WITNESSES
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ATTORNEY.
‘Patented in. ii, 193a
I‘
,104,906 ,
2,104,906
MEANs ron CASTING ROLLS
Henry'Mueller and Harry E. Walters, Pittsburgh,
Pa., assignors to United Engineering & Foundry
Company, Pittsburgh, Pa., a corporation of
Pennsylvania
Application April 6, .1935, Serial No. 15,028
5 ‘Claims.
This invention relates to the manufacture of
castings from metal which shrinks upon solidi
iying, and is more particularly concerned with
apparatus for casting rolls for use in rolling mills.
In the casting of rolling mill rolls and the like,
(01. 22-121) '
-
to keep itg liquid until the lower bearing neck
and the central portion of the casting freeze. _
In the practice of our invention we provide a
molding ?ask having substantially only heat
insulating material de?ning a molding cavity CR
positioned so the axis of the cast roll is_sub
K it is necessary to produce rolls free from blow
casting faults. Likewise it is of paramount im
stantially vertical. The heat insulating means
adjacent the upper neck portion of the casting
portance to reduce the machining requisite after
has a relatively high resistance'to the passage ~
holes, piping, segregations, pockets and other
10 casting to a minimum to save material and labor
costs.
1
.
However, in vertically casting,_substantially to
form and size, a roll having a heavy central body
portion and reduced bearing necks on either end,
,a til the metal in the neck portions solidi?es before
the metal in the heavy middle portion of the
roll. This results in the formation of a pocket
‘or ?ssure just where the upper neck portion
joins the middle portion of the roll. Thus the
of the casting is greatly reduced just
20 strength
at the point where the most strength is needed,
of heat and is substantially thick so that it func- 10
tions to maintain the upper roll neck molten for
a considerable period after casting. The heat
insulating, means adjacent the remaining por
tions of the casting have a. medium resistance. to
the passage of heat and are relatively thin and 15
have high heat conductive means positioned di
rectly behind them to absorb and conduct away.
in a rapid manner but without chilling, the heat
of the lower bearing neck and the enlarged cen-‘
tral portion of the roll casting. Thus these por 20
tions will freeze in the order named and before
and as a result roll failure has often occurred at
the upper bearing neck to produce asound cast;
‘these points of weakness which has led to the
scrapping of poorly cast rolls.
It has been proposed to eliminate the pocket
or ?ssure by casting the roll with bearing necks,
of considerably greater diameter than the diam
eter of the bearing neck after machining and as
used on the roll. In this practice the bearing
ing and one which will necessitate little machin
ing and scrap, and which will have a very‘ solid
and sound connection between the upper bear 25
ing neck and the central portion of the roll.
‘
30 neck may even be cast the same diameter as the
body portion of the roll. Methods of this char
acter may improve the strength and solidness of
Apparatus which may..be and has been'used
in the practice of our invention as just explained
is illustrated in the accompanying drawings, 01' .
which Fig. 1 is a. vertical cross-sectional view of 30
a. molding ?ask and casting constructed in ac
cordance with the principles of the invention;
, the casting, but much more metal is required and
Fig. 2 is a fragmentary cross-sectional view of a
subsequent removal of this excess material, to
portion of Fig: l, but illustrating a. modi?cation
35 bring the bearing necks to size, necessitates
of the construction thereof; and Fig. 3 is a ver
35
lengthy and expensive machining operations so ' tical cross-sectional view similar to’ Fig. 1, but
illustrating another embodiment of the invention.
that roll cost is high.
’
.
Referring to the particular embodiment of our
Extra-long or high risers have also been sug5
gested but their use‘ entails extra material in the invention seen in Fig. 1 of the drawings, the nu- '
.40 casting which must be sheared or machined o?‘ meralrl? indicates generally a ?ask, which may 40
be of any standard type, but which preferably
andscrapped and moreover difficulty in the for
mation of pockets and ?ssures is still encountered. comprises a plurality of endless-ring portions l2,
,It is the object of our invention to avoid and . M, l6 and I8 secured one on top 01.’ another in
overcome the foregoing and other di?‘iculties of, any suitable way as by the usual ?ask clamps
‘(not shown).
.
'~ 45
45 prior practices and to provide improved commer
The ?ask l0 carries molding sand 20, or other
cially feasible apparatus for casting rolls free of
casting faults and requiring little machining.
I
Our invention is predicated on our ‘discovery
that a roll with reduced bearing necks can be
50 cast substantially to form‘ in a sand mold‘ with
out the formation of casting faults so long as
the heat is bled or removed in a controlled man
__ Qner from the lower bearing neck and large cen
‘ tral portion of the roll while insuring that the
55 heat will be retained in the upper bearing neck
similar material, which de?nes the contour of
the mold and shapes the roll, indicated generally
at 28. The mill roll 28 comprises an enlarged
central portion 30 with reduced neck bearing por- 50
tions 32.and 34. The neck portion 34 is extended
vertically to provide a riser or head 36 inaccord
ance with the usual‘practice. The dotted lines
40 indicate the contour to which the casting 28 .
is preferably machined.
» ' -
a
‘55
2
2,104,906
It will be seen from the drawings that the ring
N5 of the flask I0 is made in the form of a heavy
chill which has substantially the same volume of
metal as the heavy central portion 30 of the roll
casting 28. This heav'y chill ring l6 does not func
' tion in the nature of a'etrue chill,‘ to form the cast-v
ing '28 with a hardened surface, as the chilling ac
portions. We have found that chill rings of ap
proximately the character described give the best
results. However,v it
possible to increase the
size of the chills 44 and 46 and even to make them
part ofring I8 so long as the bleeding of heat
from the lower bearing 32 follows the teachings
of our invention‘. The chill‘or heat withdrawing
rings I6, 44 and 46 are preferably of cast iron
or other material having a thermal conductivity
tion is de?nitely prevented by the layer of sand
‘20a coatingthe surface of the chillring l6. By
10 avoidingthe true chilling action and having in
' of at least two hundred B. t. u.
stead
heat bleeding operation as hereafter ex
we prevent the formation of surfacev
cracks on the cast roll which are very umdesir-_
I .able because of'necessity for heavy machining and
plaine ,
danger of roll failure from the cracks and at
10
The upper neck portion 34 of the casting 28
is adapted to be kept in a molten condition
until after the solidi?cation in turn of thebear
ing neck 32 and the main central portion 30
of the casting 28. This is achieved by providing 15
the same timev provide means whereby the amount ‘ a relatively thick refractory layer 50 at the upper '
of heat removed from the casting can vbe pre
end of the mold, which refractory may comprise
'
-
determined and controlled.
The resistance of the layer of sand-20w to the
passage of heat is very carefully determined,
either by actual experiment, by calculation, or by
both, to reach a conclusion as to its proper thick
ness. In all events the thickness is such that the
heat from the thickened portion 30 of the roll
casting 28 will be drawn to the chill ring I15 in an
. any suitable heat insulating material having a
thermal conductivity of not over approximately
two and preferably about three-quarters B. t. u,
‘By way of example, we employ a calcined semi
refractory type of diatomaceous silica. This ma- I
terial as mined is substantially of the composi- .
tion which we employ. However, to assist in the
molding thereof, we preferably grind the material
even steady flow which will cause the solidifica- - and mix it with ?re clay which functions as a
~ tion of the central enlarged portion .30 shortly
after the solidi?cation of the lower bearing neck
32.
‘
.
.
-
.
30
binder.
'
.
y.
In using the apparatus just described in the
manufacture of a mill roll, the mold is ?rst made
We have found that when casting a roll having .up in the usual manner with the axis of the mold 30
a centrally enlarged portion from about two to .substantially vertical. The steel is then cast in
about ?ve feet in diameter the sand layer 20a the mold, by any {well-known way, as for example,
should be about three-quarters of an inch. thick by bottom pouring with the aid of tangentially
for the‘ smaller size rolls and should increase in extending gates‘ (not shown) connected to the
[as thickness proportionallyfor the larger size rolls bottom
of the molding cavity. When the cast 35
with the sand being about one‘ and one-half inches ' ing is completely poured, the heat withdrawing or
thick for the largest rolls. The sand, or other chill rings 44 and 4S ?rst cause the neck portion
' molding material, formingthe layer 20a should 32 of the‘ casting to freeze with freezing extend
have a. thermal conductivity of "approximately ing gradually ‘upwardly as occasioned by the heat
40 three B. t. u. when used in the thicknesses de
withdrawing or chill‘ ring is. The refractory 40
scribed just above. (Thermal conductivity is the and heat insulating layer 50 prevent the prema
number of British thermal units passing through ture freezing of the neck portion‘ 34 as the cast
a one-inch thick layer of the‘ material 'one foot ing solidi?es from the bottom 'upwardly, and “im
square with a one degree Fahrenheit temperature purities, inclusions andthe like are carried to the ' .
4 difference on opposite sides of the layer.) This very top of the riser or head- 36 with the forma4
compares with a thermal conductivity of over tion of only‘ arelatively short pipe. The forma
three hundred B. t. u. for steeL,
',
"The lower bearing neck 32 of the casting "28 is
tion of a ?ssure or pocket at the junction of the
upper bearing neck and the central portion, of
adapted to be solidi?ed ?rst in the freezing of the , the roll is completely avoided.
'
50 casting, and this is accomplished in the embodi
In the modi?cation of the invention illustrated
ment of the invention illustrated by the provision
of chill rings 44 and 48 adjacent to the portion 32.
I
50',
in Fig. 2, the thickness of the sand layer 20a of
Fig. 1 has been changed so that the layer, indi
As will be seen from the drawings the chill‘ ‘rings. cated by the numeral 20m in Fig. 2, gradually
44 and 46 are not placed directly in contact with increases in thickness upwardly of the mold. '
the surface of the casting which would chill and This still further insures ‘freezing of the casting 55
harden the casting vsurface, but'they are spaced from the bottom gradually up to the top in that
from the casting by a covering layer 2llbof mold
themost heat will be withdrawn from the casting
ing sand.v This molding sand layer 20b functions at and near its bottom with the ,heat bleeding
similarly to the layer 20a above described in that control layer of, sand 20la getting thicker up
vc0
it servesas a refractory’or insulating layer be
wardly of the casting and finally vbecoming a dis
' 4, tween the chills and the casting, andp‘ermits a . tinct insulating layer and merging into the heat '
gradual withdrawal of the heat from the neck por-v insulating refractory 5M at the juncture of the
,tion 32 without chilling the surface of thé neck upper ‘bearing neck‘ and the roll body. The chill
portion. The character- and thickness of the ring I6| associated with the tapered-thickness
layer 2012 can be determined by the same standards sand layer 20la_ is appropriately tapered also.
as the layer 20a.
‘ The chill ring adjacent the lower bearing neck
.It is important that'the thickness ‘of the sand is numbered 441, and the ?ask and sand are idenf
layer 20b be carefully determined either analyt
ti?ed as “I, IN and ZOIQrespectively. '
ically, experimentally, ‘or both, so that the heat
‘Now referring to the embodiment of the inven
bleeding chills will‘ draw off the desired amount tion illustrated in Fig. 3, the numeral 60 indicates
of heat from the-neck portion in the desired time generally a vertically positioned cylindrical ?ask
interval.‘ Likewise, the diameter-of the chill ?lled with molding sand 62 which carries and
rings 44 and 46 is preferably such. that they ‘sub
supports cooling rings 64,‘ 66 and 68. These cool
76 stantially equal the volume of the. associated neck ing rings are preferably made of welded steel, 75
3
2,104,906
nected to the bottom of the cooling ring 64 and
water and contact with the molten‘ metal can
vsafely be said to be eliminated.
As indicated in the drawings
the arrows,
function to supply a'cooling ?uid such as water
cooling ?uid passing through the rings 64, 66, .
thereto. ‘Conduits ‘l2 and ‘It connect the various
cooling rings together while a conduit 16 func
means of~conduit 10, passes through the lower >
and are, in the embodiment shown, in the form
of hollow cylinders. Conduit means 10 are con
. tions ,to carry the cooling ?uid‘ from the rings.
Vanes ‘it are-preferably formed in conjunction
with the cooling rings to prevent the collapse of
the walls thereof and to assist in distributing
the water or other cooling ?uid around the cool
ing rings. The thermal conductivity of the cool
- ing‘rings‘will be quite high" and obviously well
in excess of two hundred B. t. u. dependent upon
15 the flow of cooling ?uid therethrough. 1
and 68 is introduced into the bottom ring (it by 5
rings, on up through the remaining rings in turn
and ?nally discharges through conduit 16. This
insures that the most cooling action is achieved
at the lower end of the casting with the cooling 10
?uid gradually warming as it is carried upwardly
through the cooling rings. Thus freezing of the
cast roll will gradually take place from the bot
tom upwardly.
‘
.
'
The heat insulating body 80 prevents the es- .>
Positioned at the top of the cooling rings is a cape of heat from the upper neck portion 90 and
cylindrical, relatively thick layer 80 of heat in-‘ ' the riser 92 and together with the‘coolinglrings
sulating material which is held in the ?ask with insures that the upper neck portion is the last
the aid of the surrounding molding sand 62, ‘or if to‘ freeze in the casting. In this manner all slag,
20 desired, gagger‘s 82, or other similar means, can blow-holes and the like are carried upwardly
be secured in the (insulating body 80 to extend ' and ?nally form a small ‘pipe at the top of the
into the molding sand to, assist in holding the riser as is illustrated. The casting, and partic
insulating body in‘the mold. The composition, ularly the joinder of the upper bearing neck and
dimensions, and function of the insulating layer the central portion of the roll, is very solid and
free of air pockets, impurities, segregations, blow :3
25 80 are similar to those above described in con
junction with the heat insulating layer 50 shown holes and the like and when machined down to
the dotted lines 94 provides a very high-grade
in Fig. 1. '
,
'
mill roll.‘
I
.\
The numeral 86 indicates generally a steel cast
From the foregoing description it will be ‘ap
ing having an enlarged central portion 88, a re
30 duced lower bearing neck 89 and a reduced upper parent that improved apparatus for casting‘
bearing‘neck 90 which vextends into a riser or metals, such as steel, which shrink on cooling, has "
been provided, and that more particularly im-’
head 92 of the casting. a The dotted lines 94 in
dicate generally the contour of the machined proved apparatus for the manufacture of mill.
rolls is provided. The disadvantages and unde—
roll obtained from the casting 86. ,
35
Positioned between the cooling rings 64, B6 and
- I 68 and the casting 86 are layers 62a and 62b of,
£10
molding sand which'prevent directv contact and
chilling of the metal of the casting against’ the
"cooling rings. The thickness of the sand layers
62a and 62b is such that they permit the ‘con
trolled withdrawing of heat from the casting por
tions. ‘The composition, thickness and function
of the layers 62a andliZb are similar to those de- "
scribed above for layers 20a and 20b. . _
' The casting “may be poured in any suitable
sirable features of priorv known practices have "
been avoided. Moreover, the apparatus is rela
tively inexpensive and requires no complicated
heating structures‘ and is readily incorporated in
standard molding ?asks.
-
While we have illustrated only certain partic
ular'embodim'ents of the invention, it will be ap
preciated that the invention is not limitedthere~v
to or thereby but is defined in the appended.
claims.
'
,
.40
,
We claim:
1'. Apparatus for casting mill rolls or the like,
manner, but preferably is bottom poured with the ‘including
a ?ask, heat insulating means com
' aid of one or more gates 96 positioned tangen
pletely
de?ning
a molding’ cavity in the ?ask,
tially of the molding surface of the neck portion the cavity being positioned
so the axis of the cast ‘
- 8,9. The size of the ?ask 60 can be increased roll is substantially vertical, said heat insulating
at one corner,'for example, to permit the in-" means surrounding the upper neck portion of the '
clusion of a vertical passage from the gates 96 to casting being substantially thick and adapted to
the top of the ?ask. This has not been illustrated maintain the surrounded portion of the casting
in the drawings as bottom pouring is old and molten, the heat insulating means adjacent sub
Well known.’
(
'
-
l
v
> stantially all the remaining portions of the casting
,
'The modi?cation of the‘ invention shown 'in being less resistant to the passage of heat, and
Fig. 2 and relating to the tapered thickness of ‘ also relatively thin, and high heat conductive
the sand or insulating layer, between the casting means positioned directly behind ‘the last re
and the heat withdrawing means, may be applied ferred to heat insulating means for readily ab
also to the apparatus of Fig. 3 as will be under
stood.
v
,
‘
,
'
In practicing our invention with the appa
ratus just described, the mold is made up in the
standard manner and in the form set forth, and
the casting is poured in-accordance with the usual
sorbing and conducting away_ heat passing there 60
through.
'
_
_
J 2. Apparatus for casting mill rolls or the like
including heat insulating means de?ning a mold
ing cavity positioned so the axis of the cast roll .
is substantially vertical, the heat insulating
means adjacent the upper neck~portion of the
and through‘the cooling ‘chambers 64, 66 and 68 casting being substantially thick and adapted to
, after the castingha's been completely poured. maintain the surrounded portion of the casting
Therefore anypossible danger is prevented which 'molten, the heat insulating means adjacent the
might result if the’ water were inlthe cooling, remaining portions of ‘the casting being less re 70
rings during the pouring with the-water leaking ‘ sistantto the passage of heat and also relatively
‘through into contact with the molten metal. It thin, and high heat conductive means positioned,
will be appreciated that‘ the cooling rings are‘ directly behind the last referred to- heat insulat
very carefully manufactured -,and tested under ing means ‘for. readily absorbing and conducting
procedure. ,- We then begin ,to pass cooling ?uid to
75 high ,i. pressures so that chances for. escape of _
l
away heat passing therethrough, said ream)?
4
_ 2,104,906
ductive means including metal jackets with cool
ing ?uid circulated therethrough.
_
'
3. Apparatus .for casting mill rolls or_ the like
including a?ask, heat insulating means de?ning
of the cast roll is substantially vertical, said’ heat
insulating means adjacent the upper neck por—.
tion of the casting having a thermal conductiv
ity of approximately three-quarters B. t. u. and
’ a molding cavity positioned so the axis ofthe ' being substantially thick and - adapted to main~
cast roll is substantially vertical, said heat in _ tain the surrounded portion of the casting molten,
sulating means surrounding the upper neck por
\ tion of the casting having a thermal conductivity
of approximately three-quarters B. t. u. and be
10 ing substantially thick and adapted to maintain
the surrounded portion of the casting molten, the
heat insulating means'adjacent the remaining
~ portions of the casting having a thermal conduc
tivity of approximately three B. t. u. and being
relatively thin, and high heat conductive means,
having a thermal conductivity of at least ap
proximately two hundred B. t. u., positioned di
rectly behind the last referred to heating in
sulating means for readily absorbing and con
ducting away heat passing‘ therethrough, said
heat conductive means including metal bodies
substantially equal in volume to the opposed vol "
’ ume of the casting.
\
the heat insulating means adjacent the rein
ing portions of the casting having a thel con
ductivity of approximately three B. t. u., and
being between three-quarters and one and one MD
half inches _ thick, and high vheat conductive
means, having a thermal conductivity of at least
approximately two hundred B. t. u., positioned
directly behind the last referred to heat insulat=
ing means 'for readily absorbing and conducting 15
away heat passing therethrough.v
5. In a mold for casting mill rolls and like
articles in a vertical position, heat removing
means adjacent the casting-for cooling the cast
ing, and insulating means of increasing thickness
upwardly oi the casting positioned between the _
heat removing means and the casting for reduc
ing and controlling the ‘?ow of heat to the ‘re
4. Apparatus ‘for casting mill rolls or the like moving means.
25 including a ?ask, heat insulating means de-‘
‘?ning a molding cavity positionedso' the axis
I
25
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