Note: Descriptions are shown in the official language in which they were submitted.
1 32~925
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BACKGROUND OF TH~ INV~NTION
Field of the Invention
The present invention relates generally to a pro~ess of
continuous casting of a mol~en metal. More specifically, the
invention relates to a technique for detecting of possible
breaking out of cast metal ln continuous casting and prevention
thereof. The invention also relates to a device for precisely
measuring temperature of casting mold, which is applicable for
detection of possible breakout of the cast metal.
Descri~tlon of the Backqround Art
Conventionally, various approaches have been taken for
detecting possibility of breakout of cast metal in continuous
casting process. In general, conventionally proposed method of
detection of breakout of the cast metal takes temperature
variation of the casting mold as parameter for detection of
breakout. For example, Japanese Patent First (unexamined)
Publication (Tokkai) Showa 57-115961 discloses a method, in which
temperature of a continuous casting mold at temperature measuring
points which are mutually different from each other in drawing
direction. The measured temperatures are compared to each other
for detecting temperature variation' thereby detecting
possibility of breakout in a cast metal. On the other hand,
Japanese Patent second (examined) Publication (Tokko) Showa 56-
7783 discloses a method of detection of possible breakout by
detecting temperature difference in copper walls of casting mold.
Furthermore, Japanese Patent First Publication (Tokkai) Showa 57-
152356 discloses employment of thermometric couple disposed in the
wall of the casting mold. In the method of Tokkai Showa 57-
1 328925
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152356, possible breakout is detected when the measured
temperature once rises above an average temperature and sub-
sequently drops below th~ average temperature.
Such conventlonal methods of detection of breakout were
not complete and not satisfactory due to the following defe~ts.
Namely, the temperature of the casting mold is variable depending
upon the casting speed. It rises as the casting speed increases
and lowers as the casting speed decreases. Therefore, there is a
possibility of mis-detection of the hreakdown of the cast metal
when casting speed fluctuat~s.
In addition, the detection of breakout of the cast metal
can be inaccurate when powder introduced between the casting mold
wall and the cast metal is uneven or formation of air gap occurs.
In order to avoid the defects in the aforementioned
prior art, there are some proposals for improvement in detection
of the possible breakout of cast metal. For example, Japanese
Patent First Publication (Tokkai) Showa 60-44163 discloses a
method of detection of the breakout, in which casting mold wall
temperatures are measured at least at two measuring points.
Judgement of possibility of breakout is made when the measured
temperature at two measuring points are inclined to higher
temperature side in relation to a normal tempera~ure level for a
given period of time. On the other hand, Japanese Patent First
Publication (Tokkai) Showa 61-2B9954 utilizes a plurality of set
reference temperatures to be compared with the measured
temperature data for detecting the breakout. Japanese Patent
First Publication (Tokkai) Showa 61-226154 utilizes present data
showing relationship of the wall temperature of the casting mold
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versus the casting speed. Utllizing the present data, a data
component in the temperature data influenced by variation of the
casting speed can be successfully avoided. Then, the temperature
data at selected one measuring polnt are compared with those
obtained from remaining measuring points. In this Tokkai Showa
61-226154, judgement of possible breakdown is made when the
relative temperature between the selected measure point and the
remainders becomes greater than an upper limit or smaller than a
lower limit.
In case of the technique shown in Tokkai Showa 60-44163,
breakout cannot be detected when the casting speed is continuously
varying or meniscus fluctuating. On the other hand, in case of
Tokkai Showa 61-2289954, the possibility of mis-detection
increases unless the set reference temperatures are adapted to the
casting conditions. Therefore, in such case, set reference
temperatures have to be adjusted depending upon the casting
condi~ions. In case of Tokkai Showa 61-226154, since it requires
precise measurement of parameters adapted to positions of the
temperature measurement and casting condition, setting has to be
adjusted every time the temperature measuring points are
differentiated or casting condition i~ changed.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to
provide a process of continuous casting including detection of a
possible breakout of a cast me~al, which can avoid influence of
variation of meniscus position and/or casting condition.
Another object of the present invention is to provide a
casting mold wall temperature measuring device which is useful for
1 32~925
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implementing the breakout detection according to the present
invention.
In a continuous casting process according to the present
invention, the factor of temperature variation speed is introduced
for detecting breakout in a cast metal. The introduction of
temperature variation speed as a parameter representative o~ the
cast metal condition is successful for avoiding the influence of
variation of the casting condition, fluctuation of the powder
introduced between the casting mold wall and the cast metal,
lo casting speed and so forth. For achieving an accurate detection
of breakout of the cast metal by introducing the temperature
variation factor, casting mold wall temperatures are measured at
various measuring points which are circumferentially aligned. The
temperature variation speed at each measuring point and the
average variation speed of all measuring points are collected and
compared for making judgement of po~sible breakout when the
difference of the temperature variation speed at each measuring
points and an average temperature variation speed becomes greater
than a predetermined value.
According to one aspect of the invention, there is
provided a method for detecting a breakout in continuous casting
comprises the steps of:
arranging a plurality of temperature measuring devices
at temperature measuring points oriented in circumferential
alignment with a given interval on a wall of a continuous casting
mold for measuring temperature of the wall at respective
temperature measuring points;
deriving variation speed of temperature at respective
1 328925
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temperature measuring points;
deriving an average temperature variation speed based on
temperature variation speed of respective temperatur~ measuring
points;
deriving a difference between the temperature variation
speed at each temperature measuring point and the average
temperature variation speed;
comparing the derlved difference with a predetermined
threshold for detecting abnormal temperature variation of each
temperature measuring point; and
observing sequential distribution and propagation of
abnormal temperature measuring points for detecting possibility of
breakout when predetermined pattern of sequential distribution
and propagation of the abnormal temperature measuring points is
detected.
According to another aspect of the invention, there is
provided a process of continuous casting comprises the steps of:
casting a molten metal to one end of a continuous
casting mold at a given controlled casting speed;
drawing solidifying cast block from the other end of the
continuous casting mold at a given casting speed;
measurlng temperature of a wall of the continuous
casting mold at a plurality of temperature measuring points
oriented in circumferential alignment with a given interval;
deriving variation speed of temperature at respective
temperature measuring points;
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deriving an average temperature variation speed based on
temperature variation speed of respective temperature measurlng
po ints;
deriving a difference between the temperature variation
72199-14
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-- 5 --
speed at each temperature measuring point an~ the average
temperature variation speed;
comparing the derived difEerence with a predetermined
threshol~ for detecting abnormal temperature variation of each
temperature measuring point;
observing sequential distribution and propagration of
abnormal temperature measuring points for detecting possibility of
breakout when predetermined pattern of sequential distribution
and propagration of the abnormal temperature measuring points is0 detected; and
controlling at least one of pouring speed and drawing
speed for preventing the cast block from causing breakout
The predetermined sequential distribution and
propagration pattern of the abnormality includes transferring of
abnormality to adjacent temperature measuring points at both
sides. The temperature measurinq points are arranged in alignment
on a plane perpendicular to the longitudinal axis of the
continuous casting mold. The temperature measuring points are
oriented downstream of meniscus.
A further aspect of the invention provides asystem
for detecting breakout in continuous casting comprises:
a plurality of temperature measuring devices arranged in
circumferential alignment with a given interval on a wall of a
continuous casting mold for measuring temperature of the wall at
respective temperature measuring points and producing casting wall
temperature indicative signals representative of the measured
temperature at respective temperature measuring points;
first means for deriving variation speed of temperature
at respective temperature measuring points;
means for deriving an average temperature variation
speed based on temperature variation speed of respective
temperature measuring points;
second means for deriving a difference between the
temperature variation speed at each temperature measuring point
and the average temperature variation speed; and
third means for comparing the derived difference with a
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predetermined threshold ~or detecting abnormal temperature
variation of each temperature measuring point, and observing
sequential distribution and propagration oE abnormal temperature
measuring points for detecting possibility of breakoUt when
predetermined pattern of sequential distributi~n and propagration
of the abnormal temperature measuring points is detected.
A still further aspect of the invention provides an
apparatus of continuous casting for casting molten metal to one
end of a continuous casting mold at a given controlled casting
speed, and drawing solidifying cast block from the other end of
the continuous casting mold at a given drawing speed, comprises:
a plurality of temperature measuring device, arranged in
circumferential alignment on the wall of the casting mold, for
measuring temperature of the wall of the continuous casting mold
at a plurality of temperature measuring points oriented in
circumferential alignment with a given interval, each of the
~emperature measuring device producing a temperature indicative
signal indicative of the measured temperature at associated
temperature measuring point;
first means for receiving the temperature indicative
signals from the temperature measuring devices and deriving
variation speed of temperature at respective temperature measuring
points to produce a temperature variation speed data;
second means for receiving the temperature variation
data from the first means and for deriving an average temperature
variation speed based on temperature variation speed of respective
temperature measuring polnts, the second means producing an
average temperature variation speed data;
third means for comparing the temperature variation data
of respective temperature measuring points with the average
temperature variation speed for deriving a difference between the
temperature variation speed data at each temperature measuring
point and the average temperature variation speed;
fourth means for comparing the derived difference with a
predetermined threshold for detecting abnormal temperature
variation of each temperature measuring point;
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fifth means for observing sequential distribution and
propagration of abnormal temperature measuring points for
detecting possibility of breakout~ when predetermined pattern of
sequential distribution and propagration of the abnormal
temperature measuring points is detected; and
sixth means for controlling at least one of casting
speed and drawing speed for preventing the cast block from causing
break out.
In a~ preferred construction, the temperature measuring
means may comprise:
a hollow cylindrical mounting bolt which is threaded to
the wall of the continuous casting mold, the mounting bolt
defining an axially extending opening;
a hollow housing disposed within the axially extending
opening, the hollow housing including first and second mutually
separated cylindrical components, which first cylindrical
component is arranged close to the wall of the casting mold and
the second cylindrical component is arranged remote from the wall;
a resilient member disposed between the first and second
components of the cylindrical housing and designed to push the
first component toward the wall;
a seal member carried by the end of the first
cylindrical component and mating with the wall surface for
establishing liquid tight seal; and
a temperature sensing element disposed within the
housing and contacting with the wall surface for monitoring the
temperature of the wall of the casting mold. The temperature
measuring device may further comprises a pushing means for
resiliently pushing the temperature sensing element toward the
wall surface.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood more fully from
the detailed description given herebelow and from the accompanying
drawings of the preferred embodiment of the invention, which,
however, should not be taken to limit the invention to the
specific embodiment but are for explanation and understanding
72199-14
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only .
In the drawings:
Fig. 1 is an explanatory section of a continuous casting
mold with cast metal in the Casting mold~ showing layout of a
plurality of temperature measuring device in circumEerential
alignment
Figs. 2(A~, 2(B) and 2(C) are chart respectively showing
variation of molten metal surface level ML, casting speed vc,
casting mold wall temperature and relative temperature variation
speed and
Pig. 3 is a section of the preferred embodiment of a
temperature measuring device which is applicable for measuring the
temperature of the casting mold wall in the continuous casting
DES~RIPTION OF ~HE PREFERRED EMBODIMENT
.. .. . .
Referring not to the drawings, particularly to Fig. 1,
the preferred embodiment of continuous casting process, according
to the present invention, introduces a feature of measurement of
temperatures of a casting mold wall 10 at a plurality of
temperature measuring points i, i~l, i+2, i+3, i-l and i-2. The
temperature measuring points i, i+l, i+2, i+3, i-l and i-2 are
oriented at positions downstream of a meniscas line M and arranged
in circumferential alignment. The temperature measuring points i,
i~l, i+2, i+3, i-l and i-2 are thus circumferentially arranged
with a given interval.
It should be appreciated that though the shown
embodiment includes one group of temperature measuring points i,
i+l, i~2, i+3, i-l and i-2 circumferentially aligned, two or more
groups of temperature measuring points may be used if desired.
For each temperature measuring points i, i+l, i+2, i+3, i-l
and i-2, a temperature measuring device 20 of Fig. 3. The
temperature measuring device 20 is inserted into the casting mold
wall of the casting mold 10 for measuring the temperature. The
temperature measuring device is designed to monitor the
temperature of the wall of the casting mold at the associated
temperature measuring point and produces a temperature indicative
signal. The detailed construction of the temperature measuring
72199-14
1 32~q25
device 20 will be discussed later.
The temperature measuring dev~ce 20 is connected to an
arithmetic circuit 40 whlch includes a temperature variation speed
derivation stage 41, an average temperature variation speed
derivation stage 42 and a discriminator stage 43. The temperature
indicative signals from respectlve temperature measuring devices
20 are at first processed by the temperature variation speed
derivation stage 41 to derive the temperature variation speed at
respective temperature measuring polnts. An average temperature
variation speed is then derived on the basis of the temperature
variation speeds at all of the temperature measuring points in the
average temperature variation speed derivation stage 42. Then,
the temperature variation speed of each temperature measuring
point is compared with the average temperature variation speed to
derive a difference in the discriminator stage 43. In the
discriminator stage, it is lurther performed to compare the
difference with a predetermined abnormal temperature variation
representative criterion to make judgement whether the temperature
variation speed of the temperature measuring point is within the
normal range or abnormal range. In the discrlminating stage 43,
pattern of propagratlon or transferring of the temperature
measuring polnts where abnormal temperature variatlon is checked
and compared wlth a preset pattern which is experimentally set in
view of the past experienced breakout The discri~inator stage
43 outputs a discriminator signal to a speed controller 50 for
controlling casting speed and/or casting speed for preventing the
cast block from causing breakout.
The process performed by the aforementioned arithmetic
circuit will be discussed in detail herebelow. Based on the
measured temperature, temperature variation speed ~i is derived
with respect to each temperature measuring point i~ i+l, i+2, i+3,
i-l and i-2. The temperature variation speed ~i can be derived
from the following equation:
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where ~i is instantaneous temperature
e'i is the temperature at ~t be~ore and
~t is a period of time.
On the other hand, average temperature variation speed av of all
of the measuring points (i = 1 to N) can be derived according to
the following equation:
N
~av l/N x ~ Bi .......... t2)
where N 19 number of temperature measuring points.
From the temperature variation speed ~i at each temperature
measuring polnt i, i~l, 1+2, i~3, i-l and i-2, ànd the àverage
temperature variation speed 0 , relative temperàture variation
speed i
can be calculated by the following equation:
~ av ---- ~3)
When the temperature variation at respective temperature measuring
points i5 caused by factor other than breakout gradient of
tempesature variation speed points becomes substantially equal at
respective temperature measuring points. Therefote, in such case,
the tempeeature vaeiation speed can be illustrated by:5
i D 9
~ i = C/s
As long as the condition set focth above is satisfied, judgement
can be made that temperature variation is caused by a factor
other than break out of the cast metal.
Hereafter will be discussed the practical process of
detection of breahout utilizing the temperature variation speed
~i at respective temperature measuring points and the average
temperature variation speed ~ . Here, it is assumed that break-
1 32~925 72199-14
out occurs at the point A on the meniscas M between the
temperature measuring points i and i+l or, in the alternative,
adjacent the temperature measuring point i. By continuing
casting, the relative temperature variation speeds ~ri and ~ir~l at
the temperature measuring points i and i+l are simultaneously
increased. Or, in the alternative, the relative temperature
variation speed ~i at the temperature measuring point i is at
first increased and subsequently, the relative temperature ~i+l is
increased. By further continuing casting, the relative temperature
variation speeds 0i_l-and ~i+2 at the temperature measuring points
i-l and i+2 are simultaneously increased. Or, in the alterna~ive,
the relative temperature variation speed ~i 1 at the temperature
measuring point i-l is increased and subsequently, the relative
temperature i+2 is increased.
As will be appreciated herefrom, when breakout occurs
in the cast block, the relative temperature variation speed
increases in order. It may also be appreciated from the above
discussion that, when breakout occurs, variation of the relative
temperature variation speed occurs simultaneously or alternatively
at both sides of the point at which the breakout occurs, in
order. To the contrary, when thermometric couple in one
temperature measuring point is damaged, variation of the relative
temperature variation speed occurs at respective temperature
measuring points in order in one direction. For instance,
assuming thermometric couple at the temperature measuring point
i-l being damaged, variation of the relative temperature variation
speed occurs in order of i - (i+l) - (i+2) ... Therefore, this
type of variation of the relative temperature variation speed can
be distinguished from that occurring upon breakout,
The variation of the temperature variation speed
occurring as set forth above was found as typical phenomena
occurring immediately before occurrence of actual breakout whish
is caused by sticking from the analysis of temperature variation
data of several tens examples.
As will be appreciated herefrom, accurate detection of
possible breakout becomes possible, according to the present
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1 328925 72199-14
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invention, by detecting abnormal temperature variation at each
temperature meaSuring point and propagration characteristics of
abnormality to adjacent temperature measuring points. Since the
manner of detection of possible occurrence o~ bcea~ut in cast
metal is made based on qualitative analysis of temperature
variation occurring at respective temperature measuring points,
the method of detection of possible breakout is applicable
without requiring substantial change of setting of the parameters.
Here, maximum abnormality propagration period (T) can be
arithmetically obtained from the following equation:
T = (w x tan B)/( x V ) ........ (5)
where w is a distance between adjacent temperature
measuring points
Vc is a casting speed
B is breaking angle of solidifying shell and
Q is constant (0.5 to 1.0)
On the other hand, number of abnormality detecting
temperature measuring points to make judgement of possible break-
out can be determined in relation to the distance Lp from the
leading end of the break line to the outlet of the casting mold,
casting speed Vc' after detection of possible breakOUt and
period of time td required for deceleration, to satisfy the
following relationship:
ks/(Lp - aVc x td)/Vc'> dB O ---- (6)
Lp = L - ~m - (n x w)/2 tan ~ ... (7)
where ks is solidifying speed constant (mm.min ) of
molten metal in casting mold
Vc is casting speed (m/min)
L is a length of casting mold (m)
dB O is experimentally obtained minimum thickness
:. .
. .
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(mm) of solidifying sh~ll which does not cause breakout by
bulging immediately below the casting mold
~m is a distance (m) from the entrance of the
casting mold to the temperature measuring points and
S n is number of abnormality detecting temperature
measuring points for detection of break~Ut of cast metal.
The number of the abnormality detecting temperature
measuring points is preferably a maximum number which can satisfy
the relationship of formula (6) set forth above. By utilizing the
greater number of temperature measuring points for making
judgement that breakout possibly occurs, occurrence of
mis-detection can be reduced.
As will be appreciated herefrom, for detecting possible
breakout the following parameters are to be set:
9cr which is upper limit value of the temperature
variation speed
t which is a minimum period of time in which is
0 maintained 9. > 9
l = cr
B, a, and n.
In practice, t is set for avoiding mis-detection lead
by temporary fluctuation of the molten metal temperature which
causes ~i 2 9 . Therefore, by providing t influence of molten
metal temperature fluctuation can be successfully avoided. B and
a can be obtained from temperature data upon occurrence of break-
out. Normally, B is set in a range of 20 to 45 and a is set in
a range of 0.5 to lØ On the other hand, n can be derived from
the aforementioned formula (6) and equation (7). Therefore, it is
practically required to two parameters, i.e. ~ and t , to be
set. These two parameters may be set based on temperature
variation pattern in experienced break out.
EXAMPLE
In order to confirm performance of detection of break-
out according to the invention, experimental casting was performed
,
1 3 2 ~ q 2 ~ 72199-14
according to the casting and temperature measuring conditions set
in the following table I.
T~BLE I
rype of Caster (Bending Type~ (Vertical Mold (Vertical Mold
~ending Bending
Type) Type)
Kind of Steel Stainless Steel teel Plate ow Carbon
illed Steel
High Carbon igh Tension Carbon
Steel Steel Killed Steel
Size of ~lock rhickness rhickness hickness
200 - 260 mm 200 - 260mm 230 - 260 mm
Width Width idth
850 - 1250 mm900 - 1900 mm800 - 1900 mm
Casting Speed
Vc (m/min)0.6 - 1.0 0.9 - 1.4 0.9 - 2.0
Temperature
variation Speed
_ 0.5 0.6 0.7
Detection
Range (m/min) 0.5 or more0.5 or more 0.8 or more
~inimum Period _
trC (sec) 6.0 4'.0 4.0
remp. Measure-
ent Depth22 - 10 mm 28 - 10 mm 33 - 10 mm
w 196 mm 150 mm 152 mm
~m 250 mm 330 mm 272 mm
L 700 mm 800 mm 900 mm
_ 20 _ 45u 20 _ 45v 20 - 45
0.5 - 0.9 0.5 - 0.9 0.5 - 0.9
n 2 3 3
During experimental casting, accuracy of detection of breah~ut
was checked. In order to compare with the result in the inventive
method, comparative experiments for detecting breakout wa~
performed in a method according to that disclosed in Tokkai Showa
61-226154, set forth above. The results are shown in the
following table II.
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TA~LE II
caster_TYe- = 1 2 3
Invention A0.003470.001310.00202
B 40% 100~ 100
C 10% 0% 0%
Comparative A0.05560.00409 0.00673
B 25~ 32~ 30%
C 18~ 18~ 16%
In table II above, A indicates occurrence of alarm per
one heat, s is a rate of occurrence of breakoUt mark on the
surface of cast block in the casting mold upon occurrence of the
alarm ((brea~ut mark occurrence 2b)/A(total occurence number of
alarm, a) x 100), C is occurrence of overlooking of breakOUt
((overlooking occurrence 2c)/(B + overlooking occurrence) x 100).
Figs. 2(A), 2(B) and 2(C) are chart showing variation of
molten metal surface level ML, casting speed Vc, casting mold wall
temperature and relative temperature variation speed during
experiment, in which possibility of breakOUt is detected. As
will be appreciated herefrom, temperature variation speed is
maintained essentially unchanged even when the casting speed Vc
and the molten metal surface level ML fluctuate
at significant level.
In the process shown in Figs. 2(A), 2(B) and 2(C),
casting speed was decelerated at the timing shown by arrow in
response to alarm for possibility of breakOUt In observation of
the corresponding portion of the cast block, marking showing 30 growth of sticking type break out appeared. From this, it is
clearly proven that method of detection of the breakOUt according
to the present invention works very effectively.
Pig. 3 shows the preferred construction o~ the
temperature measuring device which is useful for implementing the
preferred process of detection of possible breakOUt. In the
shown construction, the casting mold copper wall 10 is formed with
a plurality of groove 11 defining a cooling water path. A cooling
water box 12 has a planer section mating with the back surface of
the copper wall 10 of the casting mold to stationally support the
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copper wall. The cooling water box 12 and the copper wall 10 are
rigidly connected to each other by means of a fixing bolt 13. The
fixing bolt 13 is formed with an axially extending through opening
13a.
The temperature measuring device 20 has an inner
cylindrical housing 24 extending through the opening 13a. The
inner cylindrical housing 24 is slidably disposed within the
opening 13a and has an end section carrying water seals 24a and
24b. The rear end of the inner cylindrical housing 24 contacts
with one end of coil spring 25 which pushes the cylindrical
housing 24 toward the copper wall 10 to establish liguid tight
seal by depressing the water seal 24a. To the other end of the
coil spring 25, an outer cylindrical housing 26 contact at the
inner end. The outer cylindrical housing 26 has a threaded
section 26a which engages with a female thread formed on the inner
periphery of the opening 13a. Therefore, the outer cylindrical
housing 26 is thus threaded to the opening 13a.
The inner end of the inner cylindrical housing 24
carries a holder 27 via the water seal 24b. The holder 27 is
axially pushes by a coil spring 28. Through axially extending
openings of the cylindrical housings 24 and 26, a thermometric
couple introducing tube 29 extends. The thermometric couple
introducing tube 29 contacts with the coil spring 28 at the inner
end thereof. The thermometric couple introducing tube 29 is formed
with a threaded portion 29a. The threaded portion 29a engages
with the female thread formed on the inner periphery of the outer
cylindrical housing 26. Therefore, the thermometric couple
introducing tube 29 is fixed to the outer cylindrical housing 26.
Through the center opening of the thermometric couple
introducing tube 29, a termometric couple 30 extends to contact
the inner end to the copper wall 10. The front end portion of the
thermometric couple 30 is gripped by the holder 27. Since the
holder 27 is pushed toward the copper wall 10, by means of the
coil spring 28. The inner end of the thermometric couple 30
resiliently pushed onto the copper wall 10 to assure contact
therebetween. The pushing force of the coil spring 28 is
1 328925
regulated by a stopper member 31 which is fixed onto the outer end
portion of the outer cylindrical housing 26 and restrict axial
movement of the thermometric couple introducing tube 29 toward the
copper wall.
Sealing packing 14 is disposed between the outer end
portion of the fixing bolt 13 and the inner periphery of the
cooling water box 12 for establishing tight seal and fixing the
fixing bolt.
With the construction set forth above, the cooling water
leaked from the grooye 11 of the copper wall 10 through paths 32
and 33 can be blocked to flow into the inside of the fixing bolt
13 by the water seal 24a. On the other hand, the leaked water
flowing through paths 32, 33, 34 and 35 can be blocked by the
water seal 24b. Therefore, the thermometric couple becomes free
from influence of the leaked water. Water tight seal established
by the water seals 24a and 24b can be maintained even upon
occurrence of thermal distortion of the copper wall 10 because the
inner cylindrical housing 24 is resiliently pushed by means of the
coil spring 25 to constantly establish water tight seal by the
water seals 24a and 24b. On the other hand, as the inner end of
the thermometric couple 30 held by the holder 27 is constantly
pushed toward the copper wall 10 by the coil spring 28, contact
between the thermometric couple 30 and the copper wall 10 can be
constantly maintained for assure measurement of the temperature of
the copper wall.
In the preferred construction, the water seals 24a and
24b may be formed into O-ring and made of fluorine, fluon, metal,
such as copper, alminium, or so forth.
In the shown construction, since the thermometric couple
30 extends from the inner end of the holder 27 for a length of 1
mm to 3 mm. There may not occur buckling even when substantially
small diameter thermometric couple, such as that has 1 mm to 2 mm
diameter, is used. As is well known, smaller diameter of
thermometric couple has higher sensitivity of the temperature.
Therefore, the shown construction allows the temperature measuring
device 20 satisfactorily sensible of the copper wall temperature.
1 32~q2~
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In addition, by the shown construction, since the inner
cylindrical housing 24 carrying the water seals 24a and 24b will
not rotate when fastening the outer cylindrical housing 26 because
it is separated from the outer cylindrical housing via the coil
spring 25. Furthermore, presence of the coil spring 28 absorbs
the rotational torque to be exerted on the termometric couple
introducing tube 29 when the later is fixed to the outer
cylindrical housing 26. 8y this construction, the water seals 24a
and 24b will never be damaged upon assembling.
EXAMPLE
Experimentally, the temperature measuring device is
assembled in the following specification:
Eixing bolt 13
outer diameter: 18 mm
length : 470 mm
nominal diameter: W18
opening (inner diameter): 10 mm
material : SUS 630
Inner cYlindrical housing 24
external diameter: 9.0 mm
inner diameter: 5.5 mm
length: 400 mm
material: SUS 304
Coil spring 25
external diameter: 9.0 mm
inner diameter: 5.5 mm
spring constant: 4 kgf/mm
material: SUS 304
section: square
Outer cylindrical housing 26
external diameter: 9.0mm
inner diameter: 5.5 mm
length : 27 mm
material: SUS 304
Holder 27
material: copper
- 19 1 3 2 ~ q 2 5
Thermometric couple 30
external diameter 1.0 mm being silver brased and
extended therefrom for the length of 3 mm
Coil spring 28
external diameter: 5.0 mm
inner diameter: 3.5 mm
spring coefficient: 1 kgf/mm
material: SUS 304
Thermometric couple introducing tube 29
external diameter: 5.0 mm
inner diameter: 3.5 mm
length: 440 mm
material: SuS 304
~tilizing the above-specified temperature measuring
device, experimental measurement of the copper wall temperature
was performed. In the experiment, fluorine O-rings are used as
the water seals 24a and 24b, which O-rings are provided a
resistantive temperatures of 260 C and 200 C respectively. The
coil springs 25 and 28 are pre-loaded at 11 kg and 5 kg,
respectively. The pressure of the cooling water passing through
the cooling water path 11 is set at 8 kgf/cm2.
- During experimental measurement, leak of the cooling
water in the thermometric couple introducing tube 29 was observed.
Despite cooling water leakage, the measured temperature was stably
maintained within a range of 150 C to 350 C.
After experimental casting for 500 heats, the
temperature measuring device 20 was removed from the fixing bolt
13. In observation of the temperature measuring device 20, the
carbonized portion was found on the water seal 24a at the portion
mating with the copper wall 10. However, no leakage of the
cooling water through the water seal was observed.
The shown type of temperature measuring device is
advantageously introduced in imprementation of the preferred
method of detection of possible break out since it does not
require disassembling of the casting mold upon installation.
1 ~2~925
- 20 -
secause disassembling of copper wall upon installation of the
temperature measuring device results in releasing of the copper
wall from stress which is caused due to distortion, difficulty of
re-assembling of the casting mold may occur otherwise.
Furthermore, since the shown embodiment oÇ the temperature
measuring device can establish complete water seal, stable
measurement oE the copper wall temperature can be performed. In
addition, since the thin thermometric couple can be employed in
the temperature measuring device, satisfactorily high sensibility
is facilitated. Furthermore, since the shown temperature
measuring device is substantially compact and thus allowed to be
housed within the fixing bolt, flexibility of installation can be
conveniently established.
While the present invention has been disclosed in terms
of the prefereed embodiment in order to facilitate better
understanding of the invention, it should be appreciated that the
invention can be embodied in various ways without departing from
the principle of the invention. Therefore, the invention should
be understood to include all possible embodiments and
modifications to the shown embodiments which can be embodied
without departing from the principle of the invention set out in
the appended claims.
