Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to apparatus for obtaining a sample of
molten material.
For a long time there has been a continuing effort, particularly
by individuals associated with the steel industry3 to provide a satisfactory
method and apparatus for the collection of solidified samples of molten
- material to be used for constituent analysis. Samples have been obtained by
- pouring molten material into a mold having a cavity configuration of a
desired shape. Samples have also been obtained by immersing the closed end
of a metal or heat-resistant glass suction tube or a mold of more complex -
configuration into a bath of molten material so that upon destruction of an
end closure molten material would be sucked up into the device. Suction was
achieved either by connection to suction producing means or using a sealed
evacuated device. There have also been utilized immersible mold structures
having a top, bottom, or side entrance passage to a cavity of a desired shape,
the cavity of the mold being filled by inflow caused by gra~ity or by t~e
hydraulic head of the molten material. In these latter modifications the
sample receiving cavity must be vented to atmosphere.
It has long been known to obtain samples comprised o~ a head
portion of any desired shape attached to a stem portionO It is also known
in the prior art to employ samplers comprised of split mold structures
wherein the mating parts of the mold when placed toge~her form a sampler
having one or more sample receiving cavities, one or more vent passages for -~
venting the cavity or cavities to atmosphere and an entrance passage the ;
; normally open end of which is temporarily closed by ~ destructible ~aterial
to prevent ingress of slag which may exist in a bath of molten material by
maintaining the entrance passage closed until the sampler has been immersed
into a molten bath below the level of any slag existing therein. A relative-
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ly recent patent disclosing many of the foregoing features is United States
Patent 3,646,816 issued to Hance et al and assigned to the same assignee
as the present application.
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Samplers of the type where the molten material enters the sampler
through a passage having its opening in an end face at the immersion end of a
mold have certain advantages, however, considerable difficulty has been
experienced with such samplers due to run-out of the material being sampled
as the sampler is withdrawn from a bath of molten material thus resulting in
the samples being hollow or tubulated instead of solid all the way through.
Some difficulty has also been experienced with split mold samplers in that
molten material tends to run between the mold halves, which are almost always
slightly warped. This results in the production of unwanted flashing on the
edges of the sample.
In order to prevent loss of gas from the sample cavity of a mold
structure it is known as taught in United States Patent 3,315,529 to include,
in an evacuated apparatus for taking samples from melts, a multi-part mold
structure having a cooling jacket disposed about wall structure defining a
sample receiving cavity and wall structure defining a cavity which is a
portion of the flow passage which conveys molten material to the sample
receiving cavity. A metal plate or disk is secured between the mold sections
the walls of which define the above cavities~ This platle has a through
passage which provides a narrow or restricted path for the flow of sample
to the sample cavity. The through passage opening is provided with sharp
edges, by using any of several configurations illustrated in the patent~ and
the plate and its parts tinned or covered with a non-gassing fluxing agent
so that upon solidification of the molten material in the sample cavity the ;
material closes around the disk and will weld itself thereto particularly
if the above mentioned sharp edges are provided.
It is also taught in French Patent 1,436,377 to provide the tube
- of an evacuated glass tube type of sampler with a narrowing in order to re-
- duce the speed of circulation during the aspiration of the liquid and to
ensure the formation of a compact sample, free of hollow areas. United
States Patent 3,455,164 teaches the use of sampler bodies made of a porous
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shell molded sand. Such materials while satisfactory for
some applications are not suitable for use in a sampler
wherein it is required to exclude substances from the
sample which are given off by the resin coated binder
materials utilized in the shell molding process.
Applicant has discovered that a totally expend-
able immersion sampler device of the split mold type can
be constructed which includes means to prevent the form-
- ation of unwanted flashing on a sample while enhancing
. 10 venting in a manner to promote a uniform fill, and means --~
further promoting uniform fill and at the same time
functioning to prevent run-back, i.e. loss of sample from -
the sample receiving cavity of a mold upon withdrawal of
the sampler from the bath of molten material and which ;~
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does not require the use of a cooling jacket to cool an -
orifice plate and the walls defining cavities of a mold
to promote freezing of the sample.
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~ ccording to the present invention, there is
provided an immersion sampler cGmprising a split mold
- body with mating parts which are recessed to define a
sample cavity and a flow passage through which a sample
of molten material can flow into the cavity when the
: sampler is immersed in the molten material, and a gasket
capable of withstanding the molten material between the
mating parts for reducing the formation of flash on the
: solidified sample, the gasket being sufficiently porous ~ :
to allow venting therethrough of gas from the cavity as
the sample enters therein.
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Applicant's invention may best be understood
by reading the following description together with
reference to the various figures of drawing.
: The invention will now be described, by way of
ji example only, with drawings in which
,
. Figure 1 is a side elevation partly in section ~. :
showing the relationship between the mold, a holder
~: therefor, a closure member, and a handle or manipulator
used for immersing the mold in a bath of molten material,
Figure 2 is a sectional view along the line 2-2
` of Figure 1 with mold inserts omitted,
Figure 3 is a sectional view taken along the `
line 3-3 of Figure 1 with mold inserts omitted,
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Figure 4 is a sectional view taken along the line 4-4 of Figure
1, ,,
; Figure 5 is an exploded side elevation of the sampler of Figures
1-4 showing the location of a porous gasket in accordance with applicant~s
invention, and
Figure 6 is a plan view of the gasket of Figure 5. `
Referring to Figure 1, there is shown an i ersion sampler
device for obtaining a sample from a bath of molten material. A split mold
- 11 only one-half lla of which is shown in Figure 1 is comprised of two
- 10 identical halves which are assembled in face-to-face relation with or without
a gasket as shown in Figures 4 and 5. The mold halves are preferably made
` of a ceramic material called cordierite which is composed of alumina,
magnesia~ and silica. The mold halves may be cemented together with a
refractory cement or otherwise secured in a manner which avoids leakage of
molten material into any space between the halves which might exist should
; the faces of the mold halves not be perfectly flat. Generally the mold
halves will be slightly warped so that either a cement or a gasket should
be used. It has been found by applicant that by using a gasket made of a
material which is porous that not only is leakage of molten metal into
spaces between the mold halves prevented, thus avoiding flash or fins on the
sample upon solidi~ication of the molten material, but that additionally
more uniform venting of the sample cavity appears to be effected which
results in a complete fill with varying amounts of superheat of the molten
material. In view of the foregoing a gasket 20~ as shown in Figure 6 is
inserted between the mold halves as shown in Figure 5. The gasket 20 is
made of a porous material that will withstand exposure to the molten material
of the bath. For obtaining samples of molten steel it has been found that a
gasket about .01-.02 inch thick made of felted refractory fibers which is a
material obtainable from Refractory Products Company, Mount Prospect~
Illinois under the trademark FIBERFRAX has been found suitable. After the
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gasket is properly placed and the mold ~lalves secured as by a piece of
adhesive tape (not shown) a heat destructible cap 12 is affixed thereto.
For obtaining a sample of steel the cap :L2 is preferably thin-walled and of
mild carbon steel so that it will quickly melt away after immersion into
the bath. As is well known to those ski:Lled in the art such caps are utiliz~
ed to prevent the ingress of slag when the immersion sampler penetrates a
slag layer as it is being inserted into the molten bath to obtain a sample
therefromO Those skilled in the art have found it desirable sometimes to
include a thin coat of paper, plastic, or other suitable material on the
outside of the cap 12 to prevent slag from sticking to the cap. If slag
sticks to the cap when the cap is destroyed slag might enter the sampler
which, of course3 is undesirable. No such coat is shown on cap 12 since
it per se is not always necessary and forms no part of applicant~s invention.
It is also to be understood that when no slag is present no fusible cap is
necessary. `
= The sampler unit comprised of the assembly of the two identical
halves lla of the ~old 11 with gasket 20 between them and the cap 12 is in-
serted into the end of a protection tube 13 which may be made of cardboard,
graphite, ceramic, or other suitable material and secured therein as by
20 means of any suitable adhesive to for~ a device ready for use. As those
skilled in the art are aware, a sampler device as just described is with~
drawn from a supply thereof and pushed onto a manipulator or handle which
may be in the for~ of a black iron pipe 14 of suitable length. In order to
regulate the distance that the pipe extends into tube 13 it may be bent as
at 14a. The binding action between a cardboard tube and the bend in the
pipe, which is otherwise a loose fit within the cardboard tube, is sufficient
to secure the sampler device on the pipe. Of course other means may be used
as a tube stop an~ to secure the tube to a manipulator. -~
Since the mold halves lla are identical it is only necessary to
describe one of them. The material of the mold halves may be any which will
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withstand immersion into the molten baths at the usual bath temperature and -~
~hich ~ill not conduct heat in a manner to prevent filling of the mold.
When taking samples of molten steel the material must withstand temperatures
up to and in excess of 3,000 Fahrenheit in which case the ceramic mentioned
above is suitable. The mold piece lla may include a recess llb at the
- immersion end thereof. The term "immersion end" as utili7ed throughout the
specification and claims is intended to refer to that end of the immersion
sampler which first enters the bath of molten material. As viewed in
Figure 1 it is the lower end facing cap 12. The recesses llh together form
10 a countersunk part of a mold which can be utili~ed to support a disk 17 to ~
close an entrance port llc and may be of any material which may be melted -
- by the heat of the bath. The disk can be of a material which will melt
and thereafter mix with the molten material which enters the mold structure.
As well known to those skilled in the art it is sometimes desirable to
utilize a deoxidizing material, for example aluminum, to kill a sample of
steel as it enters the mold. For this purpose it has been found desirable
to make disk l? hat-shaped, as shown, so that it will extend into the entr-
ance port of the mold. The reference number llc designates the entrance
port which, in the device illustratedg is a part of the flow passage for
material enterjng the mold. Wall portions of the mold are constructed and
arranged to form a venturi lld. As defined in Websterls New International
Dictionary, Second Edition, Unabridgedg Published 1954, a venturi t`ube or
- venturi 1, as used in hydraulics is defined as a short tube~ inserted in a
pipe line, whose internal surface consists of two truncated cones connected
at the small ends by a very short cylinder called the "venturi throat"O In
applicant's specification and claims the term "venturi" is employed with
reference to the cone shaped sections connected by the short small diameter
passage which when the mDld halves are assembled form the venturi lld having
a venturi throat lld' The function of the venturi tube org as commonly
designated, the venturi in accordance with applicant's invention is to
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minimi~e resistance to the inward flow of molten material to the sample
cavity and effect a reduction in the pressure of the inwardly flowing
material. The venturi throat functions as a thermal valve to help prevent
` back-flow of the molten material. The thicker wall structure of the body in
the region of the throat maximizes removal of heat from the molten material
in a manner such that when the inward flow ceases the material free~es in
the throat thus trapping the sample inside the sample cavity. Applicant
has also found from an inspection of cast samples obtained from samplers
constructed in accordance with his invention that the venturi appears to
10 effect a marked reduction in splash as the molten material enters the sample -
-receiving cavity thus producing more homogeneous samples. The end of the
venturi opposite the immersion end opens into the sample cavity comprised
of the sections lle and llh of the mold.
Those skilled in the art are aware of the fact that for various
reasons the shape of the sample cavity i9 a matter of choice and may be of
almost any conceivable configuration. As shown in United States Patent
2,970,350 the cast sample may be in the form of a head and stem obtained
from a mold such as is depicted in Figure 2 of that patent or as indicated
in the description of Figure 4, column 3, lines 58-62, of that patent~ "The
20 mold body 4, which.~....... ~ is provided with a hollow space or mold cavity
5 which may contain various inserts for the purpose of producing castings of
complex configuration." While for applicantls purpose a ceramic mold is
preferred it is believed clear that the shape of the sample to be cast may
he of any desired configuration and other materials may be used for the
mold as a matter of choice to suit the application. ;
Still referring to Pigure 1, a semi-circular recess lle in each
mold half joins with a flat bottomed somewhat oval recess llh. These
recesses cooperate with similarly recessed portions of the other mold half~
when the mold halves are assembled, resulting in a sample receiving cavity
which produces a sample piece comprised of a flat head-like portion affixed
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to a round stem. As known to those skilled in the art it is customary, in
order to proYide the round stem of the sample with superior surface charac-
teristics and promote the flow of molten material into the cavity portion
formed by the recess llh, to include a tubular element 15 of heat resistant
glass, quartz, or a suitable ceramic, such as corderite which may be dis-
posed in the recesses lle and secured therein as by the use of a refractory
cement. In order that air and gas may escape t`rom the mold as the molten
material enters the mold venting means is provided. For this purpose a
groove lli is included in each mold half whichg when the mold halves are
assembled, results in the formation of a passage of small diameter which
serves together with the porous gasket 20 as means for venting the sample
cavity and hence the entire mold. To maintain the mold halves in proper
alignment it will be found desirable to provide in each mold half a projec-
tion such as a rib llf and a recess llg of complementary shape. The projec-
ting rib llf is best secn in Figure 2~ the recess llg of complementary shape
is best seen in Figure 3 and the manner in which the ribs and recesses co-
operate is best illustrated in Figure 4.
While mention has already been made of the possibility of supp- ;-~
- orting a disk of deoxidizing material such as aluminum in the recess llb, ;
it is to be understood that the amount of aluminum to be used has been found
to be somewhat critical. Too much not only spoils the sample for spectro~
- graphic analysis but also appears to cause loss of sample due to run-back.
Too small an amount of aluminum results in incomplete deoxidation of the
sample. Applicant has found that using a mold having a configuration in
accordance with his invention as shown and wlth dimensions such that the
weight of a steel casting obtained from the mold is about 87 gramsg for this
weight of steel the weight of the aluminum should be about 0.2 gramsO If
the weight of the aluminum in disk 17 needs to be augmented this can be
- accomplished by adding a quantity of deoxidizing material 16, such as alum-
inum foil, a small disk~or the equivalent weight needed in some other form in
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one of the end portions of the venturi lld, as shown in Figure 1.
The immersion sampler device as above described employs low cost
materials and is relatively inexpensive to manufacture. It is easily
broken open to retrieve the desired sample. The device used for illustrative
purposes contemplates a mold body approximately five inches long and having
- a diameter such that it may be cemented into a cardboard tube having an
inside diameter of about one and five-sixteenth inches and a wall thickness
of about one-quarter to three-eighths of an inch.
While in describing applicant's invention specific materials
have been referred to and a sample cavity having a shape to produce a ping-
pong paddle-shaped sample has been illustrated, it is clearly to be under~
stood that more than one sample cavity may be fed through a single venturi
and other changes may be made without departing from the scope of applicant~s
invention. Accordingly, the invention is to be limited only by the scope of
the appended claims.
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