US3864973A

US3864973A - Method and apparatus for determining the operating conditions in continuous metal casting machines of the type having a revolving endless casting belt

Info

Publication number: US3864973A
Application number: US343884A
Authority: US
Inventors: Charles J Petry
Original assignee: Hazelett Strip Casting Corp
Current assignee: Hazelett Strip Casting Corp
Priority date: 1973-03-22
Filing date: 1973-03-22
Publication date: 1975-02-11
Anticipated expiration: 1992-02-11

Abstract

Method and apparatus for determining the operating conditions in a continuous metal casting machine of the type having a revolving endless casting belt with a casting surface adapted to confine the molten metal and which is covered with a belt coating to insulate and protect the belt from the molten metal and a reverse surface adapted to be cooled by high velocity liquid coolant, such as water. The method and apparatus can be used to determine molten metal pool level and also to determine the belt coating condition and include one or more series of at least two heat sensing detectors, mounted with their tips in bearing relation against the moving reverse, cooled surface of the casting belt in positions to be surrounded by the high velocity liquid coolant flow. The heat sensing detectors are each encased in a compact streamlined casing so as to cause minimum disturbance to the high velocity flow of liquid coolant rushing by on both sides, and they are insulated to prevent the surrounding coolant from completely masking the temperature sensing action occurring at the tips of detectors where they bear against the moving reverse surface of the belt.

Description

United States Patent Petry METHOD AND APPARATUS FOR [75] Inventor: Charles J. Petry, Winooski, Vt.

[73] Assignee: Hazelett Strip-Casting Corporation,

Winooski, Vt.

[22] Filed: Mar. 22, 1973 [211 App]. No.: 343,884

[52] U.S. Cl 73/295, 164/4, 164/278 [51] Int. Cl. Glf 23/22, B22c 19/04, B22d 11/10 [58] Field of Search 73/295; 164/4, 154-156,

164/278, 283 R, 283 M, 283 MT [56] References Cited UNITED STATES PATENTS 1,139,888 /1915 Mellen 164/156 3,080,627 3/l963 Hoteko... 164/278 X 3,204,460 9/1965 Milnes 73/295 3,399,568 9/1968 Wilson 73/295 3,456,714 7/1969 Weiss 73/295 X 3,482,620 12/1969 Dumont-Fillon... 164/278 3,528,479 9/1970 Cole et al. 164/155 3,700,027 10/1972 Petersen 164/283 S 3,797,310 3/1974 Babcock et al. 73/295 26 29 i Zi\ 6%, p mam DETERMINING THE OPERATING CONDITIONS IN CONTINUOUS METAL CASTING MACHINES OF THE TYPE HAVING A REVOLVING ENDLESS CASTING BELT Primary E.-\'aminerRichard C. Queisser Assistant ExaminerFrederick Shoon Attorney, Agent, or Firm-Bryan, Parmelee, Johnson & Bollinger [57] ABSTRACT Method and apparatus for determining the operating conditions in a continuous metal casting machine of the type having a revolving endless casting belt with a casting surface adaptedto confine the molten metal and which is covered with a belt coating to insulate and protect the belt from the molten metal and a reverse surface adapted to be cooled by high velocity liquid coolant, such as water. The method and apparatus can be used to determine molten metal pool level and also to determine the belt coating condition and include one or more series of at least two heat sensing detectors, mounted with their tips in bearing relation against the moving reverse, cooled surface of the casting belt in positions to be surrounded by the high velocity liquid coolant flow.

The heat sensing detectors are each encased in a compact streamlined casing so as to cause minimum disturbance to the high velocity flow of liquid coolant rushing by on both sides, and they are insulated to prevent the surrounding coolant from completely masking the temperature sensing action occurring at the tips of detectors where they bear against the moving'reverse surface of the belt.

24 Claims, 6 Drawing Figures Jilin/3;)???

... wrlfiiaamm I PATENTEWBWQ 3.864.973

SHEU 2 [IF 4 PATENTEU 5 1 I975 SHEET 3 BF 4 1 METHOD AND APPARATUS FOR DETERMINING THE OPERATING CONDITIONS IN CONTINUOUS METAL CASTING MACHINES OF THE TYPE HAVING A REVOLVING ENDLESS CASTING BELT BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to method and apparatus for determining the operating conditions in a continuous metal casting machine of the type having an endless casting belt for confining the molten metal. The method and apparatus embodying this invention can be used for determining the molten metal pool level and can be used to determine the condition of the belt coating which protects and insulates the front surface of the belt from the molten metal in contact therewith.

Continuous casting machines are used to cast long lengths of metal strip or slab of preselected dimension directly from molten metal. The molten metal is confined adjacent to the front surface of a flexible endless moving metal belt which is moved along with the metal being cast as the molten metal is introduced into the machine from an external source. The molten metal is carried along by the casting belt as it solidifies, while a high velocity flow of coolant is applied along the reverse surface of the casting belt to cool it and to extract heat from the metal adjacent to the belt.

It is important that molten metal be introduced into the input region of the continuous casting machine at a rate which is effectively synchronized with the casting rate of the machine as determined by the belt travel so as to maintain the pool of molten metal in-the input of the machine at a desired level. When the infeed rate exceeds the casting rate, the pool level will creep up until suddenly the molten metal spills out and overflows out of the input. Such an overflow necessitates a difficult and expensive clean up and is hazardous to personnel and to the casting installation. When the infeed rate is less than the casting rate, the pool level will creep down into the machine allowing the molten metal being introduced to cascade down too far before reaching the pool causing splashing and turbulence within the machine. Such splashing and turbulence causes non-uniformity and segregations in the cast product. Also, the low pool level leaves too large a space above the pool containing gases or dross which can become trapped within or adjacent to the molten metal being introduced, thus causing impurities, hollows or voids in the cast product.

When the infeed rate is precisely matchedto the casting rate, these casting belt machines can be run continuously for long periods to successfully and efficiently cast large tonnages of strip or slab product.

In order to achieve optimal casting conditions, it is also important to control the condition of the insulative and protective coating on the front faces of the endless belt adjacent to the molten metal. In particular, the effectiveness of this coating in performing its function is dependant upon its thickness, its density, its uniformity of distribution, and its insulative quality or its resistance to heat transfer.

The method and apparatus of the present invention may be used with advantage to determine the pool level of molten metal being cast by a continuous belt metal casting machine. Additionally, the method and apparatus may be used with advantage to monitor the condition of the belt coating used in such machines on the contact with the molten metal being cast.

In actual practice it is extremely difficult to meter the infeed rate of molten metal and also extremely difficult to determine the level of the molten pool. In most cases the molten pool is hidden from sight by the equipment associated with the input region of the machine. Even if a small observation opening is attempted to be provided from one side, the surrounding insulation material and the slag and dross floating on the molten pool prevent accurate determinations to be made of the actual level of the molten pool.

The continuous movement of the casting belt and the high velocity liquid coolant rushing along the reverse surface of'the belt plus the heat are further impediments to determination of pool level. Since the molten metal is at its highest temperature as it is being introduced into the pool, the amount of heat flux is greatest and so an intensive and continuous cooling of the reverse surface of the belt is absolutely essential in this input and pool region.

2. Description of the Prior Art A variety of methods have previously been used in attempts to determine the pool level of molten metal being cast in such continuous casting machines. Among these methods is the use of the operators eye and electronic and mechanical sensors. Thermocouples, mounted in the side metal retaining dam, have also been utilized. However, all these electronic and mechanical methods which have been tried are generally very expensive to implement. In addition, all of these prior art techniques including visual observation have experienced more or less interference and nonresponsiveness or lapses in functioning due to heat, fumes from the molten metal and casting process, impurities or slag and dross build up as well as effects of the high velocity coolant flow, and other factors.

More recently in attempts to overcome the interference, non-responsiveness and failures of the prior art methods, the sensing of the pool level has been carried out by the use of beams of gamma rays from a radioactive cobaltsource which are sent through the input region of the machine where the pool of molten metal is intended to be located. This use of gamma ray pool level sensing techniques is expensive, complex and dangerous. In actual practice in many cases the gamma ray technique has not worked out much better than some of the earlier methods. I

With respect to the indication of the condition of the belt coating, several prior art methods have been employed. The most common method has been based on the casting machine operators subjective judgement of the appearance of coating and belt together with the appearance of the cast product as it exits from the machine. The coating condition has been indirectly determined by taking temperature readings on the surface of the solid cast as it emerges from the casting machine. A third method utilized occasional tests of the coating thickness by a magnetic or other type gauge.

All of these methods yield only a qualitative indication of the belt coating heat transfer resistance condition. Additionally, these methods may be subject to error due to interference caused by other factors such as rate of travel and temperature of the belt.

In summary, the prior art methods and apparatus for determining the pool level of molten metal and the belt coating condition in such types of continuous metal casting machines have had serious drawbacks.

SUMMARY OF THE INVENTION In the preferred embodiment to be described in detail hereinbelow, the method and apparatus of the present invention determines the molten metal pool level in a continuous casting machine of the type having an endless casting belt. This method and apparatus can be used for determining the condition of the insulative and protective coating covering the casting belts. The method and apparatus employ one or more series of at least two heat sensing detectors mounted with their tips bearing against the moving reverse, water cooled surface of the endless casting belt in positions to be surrounded by the coolant. The high velocity flow ofliquid coolant is directed against the travels along this reverse belt surface.

The first detector series is mounted to bear against the reverse, cooled surface of one of the endless casting belts and extends longitudinally in the direction of belt travel. This detector series is positioned to span the desired molten metal pool level in the casting machine. The temperature of the casting belt increases when it is in contact with the molten metal being cast. I have found that by taking the steps described further below, this increased temperature becomes distinguishable at the belt-liquid coolant interface, in spite of the presence of the high velocity coolant flow. Therefore, this first series of detectors determines the molten metal pool level by detecting such temperature increases or subsequent decreases at the various longitudinal detector locations. It is not necessary that temperature be accurately measured at each such detector bearing point. Each detector indicates when the temperature increases or decreases significantly at its location to thereby indicate when the pool level changes above or below that location.

A series of detectors extending laterally across the belt can be employed to serve the relative belt temperatures at the locations of each individual detector. In a twin-belt machine a series of detectors can be employed with both the upper and lower belts.

The best direct indication of coating condition is the temperature of the casting belt when it is in contact with the molten metal being cast. It is impractical, however, to measure belt temperature at the belt-coating interface. However, by taking the steps described further below, the temperature of the belt at the beltliquid coolant interface can be directly, quantitatively related to various coating properties, particularly coating heat transfer resistance, which reveal coating condition. Therefore, by utilizing a suitable means of data interpretation, for example a temperature-heat transfer resistance table, the temperature of the casting belt at points spaced across the belt-liquid coolant interface measured by the second detector series can be related to the coating property being monitored.

Both the first and second series of detectors are mounted in a spaced fashion laterally across the belt so that minimal interference with the high velocity continuous flow of liquid coolant results.

Each series of detectors may be utilized in conjunction with any suitable equipment for monitoring the temperatures and temperature variation which they sense.

Alternatively, the first and second detector series may be used in conjunction with automatic equipment which controls the rate of feed of molten metal into the casting machine to maintain the desired pool level or which automatically stops the casting process when the belt coating has deteriorated or become non-uniform to a degree making it ineffective in insulating and protecting the casting belt or adversely affecting the uniformity of the cast product.

The detectors in each series include a voltage generating element, such as a thermistor or contact thermocouple, embedded in a matrix of waterproof insulating material which in turn is mounted with a bearing tip of metal of good heat conductivity. This bearing contacts the voltage generating element on its interior side and contacts the reverse belt surface on its exterior side.

The detector is fitted into a streamlined jacket which presents little impedance to the high velocity flow of liquid coolant directed against it. The detector assembly is associated with a spring-loaded member whichh is appropriately mounted on the casting machine frame to correctly position the detector in the desired location to form a series. The spring urges the bearing tip of the detector assembly into contact with the moving casting belt.

The detector assembly is also constructed so that the jacket shields the generating element from lateral thermal effects due to the continuous rushing flow of coolant. The high conductivity bearing tip contacting the reverse belt surface transmits thermal energy from the belt surface.

Accordingly, it is an object of the present invention to provide a unique and novel method and apparatus for determining the molten metal pool level in continuous metal casting machine. Another aspect of the present invention enables the condition of the insulative and protective coating covering the casting belt to be continuously monitored in such a casting machine.

Other objects, aspects, and advantages of the present invention will be pointed out in, or will be understood from the following detailed description, when considered in conjunction with the accompanying drawings which are briefly described below and which show the presently preferred mode of putting this invention into practice.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational sectional view of a continuous metal casting machine equipped with a series of heat sensing detectors which determine molten metal pool level, and/or belt coating condition.

FIG. 2 is an enlargement of a portion of FIG. 1.

FIG. 3 is an enlarged cross-sectional view of this apparatus taken through plane 33 in FIG. 2 looking up, which illustrates the locations of the individual heat sensing detectors of both detector series.

FIG. 4 is an enlarged elevational sectional view of two heat sensing detectors mounted in spring loaded tubes on mounting arms taken through the broken plane 4-4 in FIG. 3.

FIG. 5 is an enlarged cross-sectional view of one heat sensing detector taken through plane 5-5 of FIG. 4 looking upward showing the streamlined shape of the upper detector jacket body.

FIG. 6 is an enlarged cross-sectional view of the same heat sensing detector taken through plane 66 of FIG.

4 looking upward illustrating the circular shape of the lower detector jacket body mounted in a spring loaded tubular holder.

Corresponding reference numerals indicate corresponding structural elements and corresponding characteristic features in each of the respective drawings.

DETAILED'DESCRIPTION An illustrative example of a continuous metal casting machine equipped with an embodiment of the present invention is shown in FIG. 1. In this casting machine molten metal 12 is supplied from a pouring box or ladle 14 and flows down through a pouring spout 16 into a tundish 18. The rate of flow from the ladle 14 to the tundish 18 is controlled by a tapered stopper 20 mounted on the end ofa control rod 22. From the tundish 18, the molten metal 12 is fed through a nozzle 24 into the input region 25 leading into a casting region C formed between spaced parallel surfaces of the upper and lower endless

flexible casting belts

26 and 28, respectively. The casting belts are fabricated from steel, or other alloys, which provide toughness and resistance to abrasion and physical damage as well as resistance to the temperature shocks and heat differential stresses undergone during casting. As shown in detail in FIGS. 2 and 4, each belt is provided with a protective and insulative coating or dressing 29 on its casting surface which is sometimes called the front surface.

The casting

belts

26 and 28 are supported on and driven by an upper and lower carriage generally indicated at 30 and 32, respectively. Both carriages are mounted on a machine frame (not shown). Each carriage includes two main rolls which support, drive and steer the casting belts. These rolls include upper and lower input rolls, 34 and 36, and upper and lower output rolls, 38 and 40, respectively.

The casting

belts

26 and 28 are guided by multiple finned back up rollers 41 (FIG. 4) so that the opposed belt casting surfaces are maintained in a preselected spaced relationship throughout the length of the casting region C. These finned back up rollers 41 may be of the type shown and described in US. Pat. No. 3,167,830.

A flexible, endless side metal retaining dam 44 is disposed on each side of the casting region between the casting belts, to define the side edges of the casting region for confining the molten metal. The side dams 44 are guided at the input end of the casting apparatus by guide members 46 which are mounted on the lower carriage 32, for example such as shown in said US. Pat. No. 3,167,830.

During the casting operation, the two

casting belts

26 and 28 are driven at the same linear speed by a driving mechanism 47 which is schematically illustrated and may, for example, be such as described in said patent. As shown in FIG. 1, the upper and lower carriages are downwardly inclined in the downstream direction, so that the casting region between the casting belts is inclined. This downward inclination facilitates flow of molten metal into the casting region C.

Tremendous heat flux is withdrawn through each casting. belt by means of a high velocity moving layer 48 of liquid coolant, shown in FIGS. 2 and 4, traveling along the reverse, cooled surfaces, 50 and 52 of the upper and lower belts, respectively. The liquid coolant, preferrably water containing a suitable corrosion inhibitant, is applied at high velocity, and the fast flowing layer 48 may be maintained in a manner as shown in said patent.

After the casting has solidified as indicated at 58 at least on all external surfaces, and has been fed out of the casting machine, it may be conveyed and guided by a number of feed rollers 60, two of which are shown in FIG. 1.

In order to determine the position of the pool P of molten metal in the input region of the machine, there is a series 62 (FIGS. 1 and 2) of five heat sensing detectors, 62a, 62b, 62c, 62d, and 62e which engage against the cooled reverse surface 52 of the lower belt 28 near the input region 25 of the machine. As many of these detectors as is desirable may be used for obtaining the required accuracy in locating the pool level. Still, the number of detectors in the series 62 should not be so great as to significantly obstruct the rushing flow of liquid coolant 48 travelling along the reverse surface 52 of the belt. As shown, each detector 62a-62a in this series is mounted with its tip bearing against the reverse, cooled surface 52 of the lower casting belt 28.

It is noted that these heat sensing detectors 62a-62e are positioned between the finned back up rollers 41 discussed above so that these detectors avoid interference with the back up rollers. Each detector is mounted on an

individual support arm

64a, 64b, 64c, 64d, and 64e, which is permanently mounted on and laterally extends from the lower carriage 32. The first detector 62a, or the first and second detectors 62a and 621), or more of them, may be mounted in the grooves 63 of the lower input roll 36 between the ridges 65 of this roll so as to be beneath the upstream limit of the pool P. A mounting finger 69 extends upstream from the arm 64c into the respective grooves 63 for supporting the respective detectors in the groove or grooves. However, any suitable means for mounting the detectors in a fixed location in bearing relation with the reverse cooled belt surface may be employed.

Instead of engaging the lower belt, it is also possible to determine the location of the pool P by mounting the detector series 62 to bear against the reverse, cooled surface 50 of the upper casting belt 26, near the input region 25.

In the case of a twin-belt casting machine as shown, in certain instances it may be advantageous to utilize a series of detectors 62 and another series 162 engaging the reverse surfaces of both casting

belts

26 and 28 for determining the position of the pool P. It may be advantageous to utilize a series of detectors 70 and another series engaging the reverse surfaces of both

belts

26 and 28 for monitoring the condition of the belt coating or coatings.

If desired, all four series of

detectors

62, 162, 70 and 170 may be used in a twin-belt casting machine. Alternatively, any combination of one, two, three or four of the series of

detectors

62, 162, 70 and 170 can be used. It is noted that the

detector series

162 and 170 for the upper belt are located further downstream than those for the lower belt because the downward inclination of the casting region C causes the molten surface menisccus of the pool P to be positioned at an oblique relationship to both casting

belts

26 and 28, as seen in FIGS. 1 and 2.

The pool level detector series, 62a 62e, is positioned to span the desired molten metal pool position, that is, the series 62 extends longitudinally, (i.el, upstream-downstream) in the direction of belt travel; the

leading detector 62a is positioned at a point above the desired pool position; and the trailing detector 62e is positioned at a point below the desired pool position. The remaining detectors, 62b, 62c, and 62d, are positioned intermediate the leading and trailing detectors, 62a and 62e, respectively.

Each heat sensing detector is responsive to localized changes in belt temperature on the lower reverse, cooled belt surface 52 adjacent to its own tip. As noted, when a localized region of the casting belt is in contact with the molten metal being cast, the temperature of the reverse surface of the casting belt increases in that region due to the increased amount of heat transfer occurring. In view of the intensive cooling action of the rushing coolant 48, the amount of temperature increase at the reverse surface 52 is not very great, but is can be effectively sensed by following the steps described herein. Thus, the detector series 62 senses an upstream or downstream shifting in position of the pool P by sensing a localized increase or decrease in belt temperature at the respective longitudinal locations of the

detectors

62a, 62b, 62c, 62d and 62e or of the

detectors

162a, 162b, 1620, 162d and l62e (or of all of them) in the direction of belt travel.

Each of these detectors in the series 62 or 162 (or both) is connected to a pool level data output monitor 66 (FIG. 1), which may be any suitable monitor means for indicating the response to temperature change registered by individual detectors in this

pool level series

62 or 162. For example, monitor 66 may include a sequence of electrical relays controlling colored lights, each relay being responsive to a corresponding detector 62a 62s or 162a 162e. An electrical circuit associated with each relay causes the light to become energized when its corresponding detector senses a significant temperature increase. The casting apparatus operator can then manually adjust control means 71 for regulating the flow of molten metal into the casting machine until the desired pool level is being maintained. Any other monitor means such as a sequence of recording pens or audible signals may similarly be employed. The control means 71 may include a manually adjustable or motor driven feed screw for raising or lowering the stopper to regulate the molten metal feed.

Alternatively, the pool level data output monitor and control 66 may include automatic control equipment to regulate the rate that molten metal 12 is fed into the casting machine. As shown in FIG. 1, the pool level monitor 66 is connected by circuits 67 to the feed control means 71 which moves the tappered stopper 20 through the control rod 22 and thereby controls molten metal flow. The motor driven feed screw control 71 may include a servomechanism operatively connected to the control equipment 66 so that the control of molten metal infeed is fully automatic.

As shown in FIG. 3, the pool position detector series, 62a 62e, is staggered across the belt width to avoid any significant obstruction from occurring in the continuous high velocity coolant layer 48. The staggered detector arrangement shown interfers minimally with this coolant flow. As seen in FIG. 3, some of the detectors in the series 62 are positioned in the grooves 63 between the lands 65 of the roll 36.

In the above methods of controlling the position of the pool P the rate of molten metal infeed into the input region 25 is controlled either manually or automatically to match the metal infeed to the casting rate as determined by the rate of travel of the

belts

26 and 28.

Another method which can be used in some cases to control the pool position is to stabilize the rate of infeed of the molten metal 12 at a desired value and then gradually to vary the speed of the machine by slight amounts to match the actual input of metal. As shown in FIG. 1, the pool level control equipment 66 is connected by electrical circuit means 73 to the drive mechanism 47 for the two

belts

26 and 28. This drive mechanism turns the

rolls

38 and 40 simultaneously and synchronously to revolve the belts as is indicated schmatically in FIG. 1. Also, the control equipment 66 is connected by circuit means 75 to the drive mechanism 76 for driving the outfeed conveyor rolls 60. Thus, the speed of the casting machine and outfeed rolls 60 can be automatically matched to the rate of infeed of molten metal to control the position of the pool P if the machine and roll speed is gradually varied by small amounts.

In most cases it is preferrable to regulate the infeed rate of the molten metal while keeping the casting machine running at constant speed. The reason for maintaining the casting machine at constant speed is to facilitate the operation of the rolling equipment and cast product handling equipment which is often located in line with the casting machine.

In order to monitor the condition of the belt coating 29, a second series 70 or (FIGS. 1, 2) of five

heat sensing detectors

62e, 70a, 70b, 70c, and 70d (FIG. 3) may be installed on one or both belts. These are preferably located as shown in FIG. 3 at uniformly spaced points across the width of the belt 28. As many of these detectors in

series

70 or 170 may be used as desired to provide a desired number od data sensing locations for closely monitoring the condition of the belt coating 29. Again, it is to be noted that the

series

70 and 170 should not be of such a large number as would interfer with the flow F of the liquid coolant,

If desired, as shown in FIG. 3 the trailing detector 62v in the pool level detector series 62 forms one of the detectors in the coating condition monitor series 70. This latter series is also mounted to bear against the reverse, cooled surface 52 of the lower casting belt 28. In the series 70 (and 170) all detectors may be mounted on a single supportarm Me or l64e upon which the detector 62c or 162e common to both series 62 and 70 (or 162 and 170) is mounted.

Any other suitable mounting means may be employed which fixes the coating condition detector series at a given location in bearing relation with the reverse, cooled surface of the casting belt.

The belt coating

condition detector series

70 or 170 is positioned in line with the trailing pool level detector 62e or l62e because it is at this longitudinal belt location that molten metal should always be in positive contact with the full width of the casting belt. An indication of coating condition is the temperature of the reverse belt surface when the coating on the front belt surface is in contact with the molten metal being cast. Therefore, the coating condition detector series is positioned at laterally spaced positions across the belt near the pool P.

As shown in FIG. 3, the coating

conditions detector series

62e, 70a, 70b, 70c, and 70d, is connected to a coating condition data output monitor 72. This monitor 72 includes a series of temperature indicators which register the respective temperatures sensed by these detectors. The casting machine operator may relate the temperatures to various belt coating properties using data interpretation tables based upon past operating experience for the type of coating 29 being used. It is to be understood that the detector series 170, if used, is connected to the monitor 72.

Alternatively, the coating condition data output monitor 72 may be connected to the

drive mechanisms

47 and 76 to automatically stop the casting machine when the belt coating has deteriorated or become nonuniform to a degree making it ineffective of performing its insulative and protective functions for casting quality product.

The embodiment of the heat sensing detector used in both the pool level and coating

condition detector series

62 and 70 is illustrated in detail in FIGS. 4, 5, and 6. FIG. 4 illustrates

detectors

62c and 62d in elevational cross-section. Each detector includes a jacket 80 which is fabricated from a smooth surfaced material of low heat conductivity such as polytetrafluoroethylene, e.g. Teflon which is streamlined to present little resistance to the flow F of liquid coolant 48 rushing by on either side. At and near its tip end, which contacts the reverse surface 52 of the moving casting belt 28, the jacket 80 is formed with a streamlined cross-section. This streamlined cross-section, indicated at 82 and shown in detail in FIG. 5, is defined by a parabolic leading face 84 and a V-shaped cusp trailing face 86. The direction of high velocity coolant flow F is indicated by arrows. Slippery plastic 80 reduces friction on belts. At its mounting end, the insulating jacket 80 is formed with a circular cross-section as indicated at 88 in FIG. 6. The lower circular portions of the jackets 80 are slip fitted into tubular brackets 90 which are mounted on the respective supporting

arms

64c and 64d. A spring 92 is interposed between the telescoped end of the detector and the mounting arm and urges the jacket 80 toward the reverse belt, cooled surface 52.

Each insulating jacket 80 is provided with an axial bore 94, into the end of which a thermally highly conductive metal sleeve 100, for example of copper, is press fitted. This thermally conductive sleeve 100, mounted in the very tip of the insulating jacket 80 is formed with a closed end 102 which directly contacts and slides against the moving belt surface 52. A heatresponsive voltage generating element 104, such as a thermistor or contact thermocouple, having lead wires 106, is inserted into the thermally conductive sleeve 100 in contact with its closed end 102 and is potted therein an electrically insulative, waterproof material 108 such as epoxy plastic. The lead wires 106 are connected to the appropriate monitor and control means 66 or 72.

The capped sleeve 100 is press fitted into the jacket 80 to resist movement within the jacket to insure that the capped sleeve remains in firm contact with the moving belt.

Heat is conducted from the belt, through the closed I end 102 of the cap and into the thermistor 104. After the detector series have been mounted in position the monitors 66 and 72 are set up for the desired response.

This detector arrangement insulates the heat responsive element 104 from lateral cooling effects caused by the coolant flow. However, axial heat flux travelling from the molten metal, conducted through the belt and belt-engaging cap are readily detected.

This invention enables the operating condition of a continuous metal casting machine to be continuously monitored and determined by sensing temperature changes at the moving reverse liquid-cooled surface of 5 one or both casting belts in a turn-belt machine.

This invention may also be employed to advantage with the casting belt of a wheel-and-belt casting machine for monitoring the operating condition of the machine such as the molten pool level at the input and the condition of the belt coating. Such a wheel-and-belt type casting machine is shown in US. Pat. No. 3,429,363.

Although a specific embodiment of the invention has been disclosed herein in detail, it is to be understood that this is for purposes of illustration. This disclosure is not to be construed as limiting the scope of the invention, since the described method and structure may be changed in details by those skilled in the art in order to adapt the molten metal'pool position and belt coating condition monitoring apparatus and method to particu lar casting machines, without departing from the scope of the following claims.

I claim:''

1. The method of determining the molten metal pool position in the input region of a continuous metal casting machine of the type having at least one endless, flexible, revolving casting belt with a casting surface which engages the molten metal to be cast and a reverse, cooled surface along which is directed a substantially continuous high velocity flow of liquid coolant, the casting surface being covered with a belt coating to insulate and protect the belt from the molten metal and to control the rate of cooling of the molten metal, said method comprising:

predeterming the desired range in operation of the position of the molten metal pool in the input region of the casting machine; positioning a series of at least two heat sensing detectors in bearing contact with the moving reverse, cooled surface of the casting belt and in upstreamdownstream spaced relation with respect to the direction of travel of the belt in respective positions to span the desired predetermined range in pool position; v 45 arranging said detectors to present minimal interference to the continuous high velocity flow of liquid coolant directed along the reverse, cooled belt surface; insulating said heat sensing detectors from the high velocity flow of coolant rushing by them; and

monitoring the responses of said detectors to changes in the temperature of the moving reverse cooled surface of the belt at the respective upstreamdownstream positions of said detectors to determine the position of the molten metal pool.

2. The method of determining the molten metal pool position in the input region of a continuous metal casting machine as claimed in claim 1, including the steps of 60 streamlining said heat sensing detectors to minimize the interference with the high velocity coolant flow; and

continuously pressing said heat sensing detectors against the moving reverse, cooled surface of said casting belt.

3. The method of determining the molten metal pool position in the input region of a continuous casting machine as claimed in claim 1 wherein the machine is of the twin belt type having an upper and lower belt and in which:

said heat sensing detectors are positioned beneath the lower belt in bearing contact with the moving, reverse, liquid-cooled surface of the lower belt in respective positions to span the desired location of the upstream edge of the molten metal pool.

4. The method of determining the molten metal pool position in the input region of a continuous metal casting machine as claimed in claim 1 wherein the machine is of the twin belt type having an upper and a lower belt and in which:

said heat sensing detectors are positioned in bearing contact with the moving, reverse, liquid-cooled surface of the upper belt in respective positions to span the desired location of the edge of the molten surface meniscus of the pool in contact with the upper belt.

5. The method of determining the molten metal pool position in the input region of a continuous metal casting machine as claimed in claim 1, including the additional steps of positioning a second series of at least two heat sensing detectors in bearing contact with the moving reverse, cooled surface of the casting belt in laterally spaced relationship across the width of the belt and located immediately downstream from the desired range in pool position; and

monitoring the responses of said detectors to change in the temperature of the moving reverse cooled surface ofthe belt at the respective lateral positions to determine the condition of the insulative belt coating immediately downstream from the molten metal pool while the casting machine is running and the position of the pool is being controlled to keep it within the desired predetermined range in operation.

6. The method of determining the molten metal pool position in the input region of a continuous metal casting machine as claimed in claim 1, wherein there is a grooved roll associated with the casting belt near the input region, including the steps of positioning at least one of said heat sensing detectors in a groove of said roll in bearing contact with the moving, reverse, liquid-cooled surface of the casting belt.

7. The method of determining the molten metal pool position in the input region of a continuous metal casting machine as claimed in claim 1, including the step of laterally staggering the positions of said detectors to present minimal interference to the high velocity flow of liquid coolant along the reverse surface of the casting belt.

8. The method of determining the operating conditions of a continuous metal casting machine of the type having at least one endless flexible, revolving casting belt with a casting surface which engages the molten metal to be cast and a reverse, liquid-cooled surface along which is directed a substantially continuous high velocity flow of liquid coolant, said casting surface being covered with a belt coating to insulate and protect the belt from the molten metal, said method including the steps of:

predetermining the desired operating conditions at predetermined positions in the machine;

positioning a series of heat sensing detectors in bearing contact with the moving, reverse, liquid-cooled surface of the casting belt near said predetermined positions;

urging said heat detectors against the moving, reverse surface of the casting belt to obtain heat transfer therefrom;

arranging said series of heat sensing detectors to present minimal interference to the high-velocity flow of liquid coolant directed along the moving, reverse belt surface;

insulating said heat sensing detectors from the high velocity flow of liquid coolant rushing by them; and

monitoring the responses of said series of heat sensing detectors for determining the operating conditions of the casting machine as molten metal is being cast therein.

9. The method of determining the operating conditions of a continuous metal casting machine as claimed in claim 8, including the steps of:

predetermining the desired belt coating operating conditions at predetermined positions spaced across the width of the casting belt; and

positioning said series of heat sensing detectors in bearing contact with the moving, reverse, liquidcooled surface of the casting belt at said predetermined positions spaced across the width of the casting belt to monitor the belt coating conditions as molten metal is being cast.

10. The method of determining the operating conditions of a continuous metal casting machine as claimed in claim 8, including the steps of:

predetermining the desired range in operating locations of the molten metal pool in the input region of the casting machine; and

distributing said series of heat sensing detectors in positions relatively spaced upstream and downstream along the casting belt to span said desired range in operating positions of the molten metal pool, thereby to determine the location of the pool as the molten metal is being cast.

11. Apparatus for determining the operating conditions in a continuous metal casting machine of the type having at least one endless flexible revolving casting belt with a casting surface which engages the molten metal to be cast in a' casting region as confined by the belt, said belt having a reverse, liquid-cooled surface along which is directed a substantially continuous high velocity flow of liquid coolant, and the casting surface of said belt being covered with a belt coating to insulate and protect the belt from the molten metal and to control the rate of cooling of the molten metal, said apparatus comprising:

support means attached to the continuous metal casting machine near the casting region;

a series of at least two heat sensing detectors mounted on said support means and located at spaced positions near said casting region;

said support means holding detectors in bearing contact with the moving reverse, cooled surface of said casting belt near said casting region;

said detectors being arranged to present minimal interference to the continuous high velocity flow of liquid coolant directed along the reverse belt surface;

thermal insulation material associated with said heat sensing detectors for insulating them from the high velocity flow of liquid coolant rushing by; and

monitor means connected to said heat sensing detectors to monitor the responses of said detectors to changes in the temperature of the moving reverse surface of the belt at the respective upstreamdownstream positions thereof to determine the molten metal pool position.

12. Apparatus for determining the operating conditions in a continuous metal casting machine as claimed in claim 11 in which,

said heat sensing detectors each include a tip of material of high thermal conductivity; and

said support means include spring means urging the tips of said heat sensing detectors firmly against the moving, reverse, liquid-cooled surface of the belt.

13. Apparatus for determining the operating conditions in a continuous metal casting machine as claimed in claim 12, in which said thermal insulation material is formed as a jacket surrounding said tip; and

said jacket is streamlined with respect to the flow of high velocity coolant.

14. Apparatus for determining the operating conditions in a continuous metal casting machine as claimed in claim 11 in which said thermal insulation material is a jacket surrounding the heat sensing detector and formed of slippery material to minimize sliding friction against the reverse surface of the casting belt.

15. Apparatus for determining the operating conditions in a continuous metal casting machine as claimed in claim 11, wherein there is a molten metal pool at the input to the casting region and in which: 7

said series of heat sensing detectors are located in relative upstream and downstream positions in relation to travel of the casting belt near the input to said casting region to span the desired location of the molten metal pool.

16. Apparatus for determining the molten metal pool position in a continuous metal casting machine as claimed in claim 15 wherein there is a grooved roll having lands thereon supporting the casting belt near the input to the casting region, in which:

said support means include at least one finger extending between the lands on said roll; and

at least one heat sensing detector positioned in a groove between the lands of said roll and being mounted on said finger.

17. Apparatus for determining the molten metal pool position in a continuous metal casting machine as claimed in claim 15, including a second series of at least two heatsensing detectors mounted on said support means and positioned in laterally spaced relation across the width of the belt immediately downstream from the pool position; said detectors being in bearing contact with the moving reverse, cooled surface of said casting belt; and monitor means connected to said second series of heat sensing detectors to monitor the responses of the detectors of the second series to changes in temperature of the moving reverse belt surface at the laterally spaced positions of said detectors for indicating the conditionof the belt coating at said laterally spaced positions.

18. Apparatus as claimed in claim 11 wherein each of said heat sensing detectors comprises:

a thermal insulating jacket having a tip portion and a mounting portion,

a heat conducting metal sleeve mounted in the tip portion of and protected by said insulating jacket. said sleeve having a closed heat conducting end which contacts the moving reverse surface of the belt, and

a heat responsive, voltage generating element within said jacket in heat conducting relationship with said sleeve.

19. Apparatus as claimed in claim 18 wherein the mounting portion of each of said heat sensing detectors is slidably mounted in a tube, said tube being mounted on said support means, and an internal spring disposed within said tube urging the tip of the detector into firm contact with the moving reverse, cooled surface of the belt.

20. Apparatus as claimed in claim 18 wherein the tip portion of said jacket is streamlined to present minimal interference to the high velocity flow of liquid coolant directed along the reverse, cooled belt surface.

21. Apparatus as claimed in claim 18, in which said thermal insulating jacket is formed of a slippery material to minimize abrasion against the moving reverse surface of the casting belt.

22. Apparatus as claimed in claim 18 in which the tip portion of said thermal insulation jacket surrounds said heat conducting metal sleeve; and said voltage generating element is located within said sleeve adjacent to its closed end to insulate said voltage generating element from cooling effects of the high velocity flow of liquid coolant, while conducting heat from the reverse sur-' face of the belt to said voltage generating element.

23. Apparatus as claimed in claim 11, in which:

said support means extends across near the reverse surface of the casting belt; and

said series of heat sensing detectors are mounted on said support means and are located at spaced positions across the width of the casting belt near the casting region for monitoring the condition of the belt coating as the molten metal is being cast.

24. Apparatus as claimed in claim 11, wherein said machine is a twin-belt casting machine having an upper and a lower casting belt, and in which:

at least two series of heat sensing detectors are included;

said support means being associated with both belts and holding a first series of said detectors in contact with the moving, reverse, liquid-cooled surface of the lower belt near the casting region; and

said support holding a second series of said detectors in contact with the moving, reverse, liquid-cooled surface of the upper belt near the casting region, whereby the operating condition of both casting belts is monitored as the molten metal is being cast.

Claims

1. The method of determining the molten metal pool position in the input region of a continuous metal casting machine of the type having at least one endless, flexible, revolving casting belt with a casting surface which engages the molten metal to be cast and a reverse, cooled surface along which is directed a substantially continuous high velocity flow of liquid coolant, the casting surface being covered with a belt coating to insulate and protect the belt from the molten metal and to control the rate of cooling of the molten metal, said method comprising: predeterming the desired range in operation of the position of the molten metal pool in the input region of the casting machine; positioning a series of at least two heat sensing detectors in bearing contact with the moving reverse, cooled surface of the casting belt and in upstream-downstream spaced relation with respect to the direction of travel of the belt in respective positions to span the desired predetermined range in pool position; arranging said detectors to present minimal interference to the continuous high velocity flow of liquid coolant directed along the reverse, cooled belt surface; insulating said heat sensing detectors from the high velocity flow of coolant rushing by them; and monitoring the responses of said detectors to changes in the temperature of the moving reverse cooled surface of the belt at the respective upstream-downstream positions of said detectors to determine the position of the molten metal pool.

2. The method of determining the molten metal pool position in the input region of a contInuous metal casting machine as claimed in claim 1, including the steps of streamlining said heat sensing detectors to minimize the interference with the high velocity coolant flow; and continuously pressing said heat sensing detectors against the moving reverse, cooled surface of said casting belt.

3. The method of determining the molten metal pool position in the input region of a continuous casting machine as claimed in claim 1 wherein the machine is of the twin belt type having an upper and lower belt and in which: said heat sensing detectors are positioned beneath the lower belt in bearing contact with the moving, reverse, liquid-cooled surface of the lower belt in respective positions to span the desired location of the upstream edge of the molten metal pool.

4. The method of determining the molten metal pool position in the input region of a continuous metal casting machine as claimed in claim 1 wherein the machine is of the twin belt type having an upper and a lower belt and in which: said heat sensing detectors are positioned in bearing contact with the moving, reverse, liquid-cooled surface of the upper belt in respective positions to span the desired location of the edge of the molten surface meniscus of the pool in contact with the upper belt.

5. The method of determining the molten metal pool position in the input region of a continuous metal casting machine as claimed in claim 1, including the additional steps of positioning a second series of at least two heat sensing detectors in bearing contact with the moving reverse, cooled surface of the casting belt in laterally spaced relationship across the width of the belt and located immediately downstream from the desired range in pool position; and monitoring the responses of said detectors to change in the temperature of the moving reverse cooled surface of the belt at the respective lateral positions to determine the condition of the insulative belt coating immediately downstream from the molten metal pool while the casting machine is running and the position of the pool is being controlled to keep it within the desired predetermined range in operation.

8. The method of determining the operating conditions of a continuous metal casting machine of the type having at least one endless flexible, revolving casting belt with a casting surface which engages the molten metal to be cast and a reverse, liquid-cooled surface along which is directed a substantially continuous high velocity flow of liquid coolant, said casting surface being covered with a belt coating to insulate and protect the belt from the molten metal, said method including the steps of: predetermining the desired operating conditions at predetermined positions in the machine; positioning a series of heat sensing detectors in bearing contact with the moving, reverse, liquid-cooled surface of the casting belt near said predetermined positions; urging said heat detectors against the moving, reverse surface of the casting belt to obtain heat transfer therefrom; arranging said series of heat sensing detectors to present minimal interference to the high-velocity flow of liquid coolant directed along the moving, reverse belt surface; insulating said heat sensing detectors from the high velocity flow of liquid coolant rushing by them; and monitoring the responses of said series of heat sensing detectors for determining the operating conditions of the casting machine as molten metal is being cast therein.

9. The method of determining the operating conditions of a continuous metal casting machine as claimed in claim 8, including the steps of: predetermining the desired belt coating operating conditions at predetermined positions spaced across the width of the casting belt; and positioning said series of heat sensing detectors in bearing contact with the moving, reverse, liquid-cooled surface of the casting belt at said predetermined positions spaced across the width of the casting belt to monitor the belt coating conditions as molten metal is being cast.

10. The method of determining the operating conditions of a continuous metal casting machine as claimed in claim 8, including the steps of: predetermining the desired range in operating locations of the molten metal pool in the input region of the casting machine; and distributing said series of heat sensing detectors in positions relatively spaced upstream and downstream along the casting belt to span said desired range in operating positions of the molten metal pool, thereby to determine the location of the pool as the molten metal is being cast.

11. Apparatus for determining the operating conditions in a continuous metal casting machine of the type having at least one endless flexible revolving casting belt with a casting surface which engages the molten metal to be cast in a casting region as confined by the belt, said belt having a reverse, liquid-cooled surface along which is directed a substantially continuous high velocity flow of liquid coolant, and the casting surface of said belt being covered with a belt coating to insulate and protect the belt from the molten metal and to control the rate of cooling of the molten metal, said apparatus comprising: support means attached to the continuous metal casting machine near the casting region; a series of at least two heat sensing detectors mounted on said support means and located at spaced positions near said casting region; said support means holding detectors in bearing contact with the moving reverse, cooled surface of said casting belt near said casting region; said detectors being arranged to present minimal interference to the continuous high velocity flow of liquid coolant directed along the reverse belt surface; thermal insulation material associated with said heat sensing detectors for insulating them from the high velocity flow of liquid coolant rushing by; and monitor means connected to said heat sensing detectors to monitor the responses of said detectors to changes in the temperature of the moving reverse surface of the belt at the respective upstream-downstream positions thereof to determine the molten metal pool position.

12. Apparatus for determining the operating conditions in a continuous metal casting machine as claimed in claim 11 in which, said heat sensing detectors each include a tip of material of high thermal conductivity; and said support means include spring means urging the tips of said heat sensing detectors firmly against the moving, reverse, liquid-cooled surface of the belt.

13. Apparatus for determining the operating conditions in a continuous metal casting machine as claimed in claim 12, in which said thermal insulation material is formed as a jacket surrounding said tip; and said jacket is streamlined with respect to the flow of high velocity coolant.

15. Apparatus for determining the operating conditions in a continuous metal casting machine as claimed in claim 11, wherein there is a molten metal pool at the input to the casting region and in which: said series of heat sensing detectors are located in relative upstream and downstream positions in relation to travel of the casting belt near the input to said casting region to span the desired location of the molten metal pool.

16. Apparatus for determining the molten metal pool position in a continuous metal casting machine as claimed in claim 15 wherein there is a grooved roll having lands thereon supporting the casting belt near the input to the casting region, in which: said support means include at least one finger extending between the lands on said roll; and at least one heat sensing detector positioned in a groove between the lands of said roll and being mounted on said finger.

17. Apparatus for determining the molten metal pool position in a continuous metal casting machine as claimed in claim 15, including a second series of at least two heat sensing detectors mounted on said support means and positioned in laterally spaced relation across the width of the belt immediately downstream from the pool position; said detectors being in bearing contact with the moving reverse, cooled surface of said casting belt; and monitor means connected to said second series of heat sensing detectors to monitor the responses of the detectors of the second series to changes in temperature of the moving reverse belt surface at the laterally spaced positions of said detectors for indicating the condition of the belt coating at said laterally spaced positions.

18. Apparatus as claimed in claim 11 wherein each of said heat sensing detectors comprises: a thermal insulating jacket having a tip portion and a mounting portion, a heat conducting metal sleeve mounted in the tip portion of and protected by said insulating jacket, said sleeve having a closed heat conducting end which contacts the moving reverse surface of the belt, and a heat responsive, voltage generating element within said jacket in heat conducting relationship with said sleeve.

22. Apparatus as claimed in claim 18 in which the tip portion of said thermal insulation jacket surrounds said heat conducting metal sleeve; and said voltage generating element is located within said sleeve adjacent to its closed end to insulate said voltage generating element from cooling effects of the high velocity flow of liquid coolant, while conducting heat from the reverse surface of the belt to said voltage generating element.

23. Apparatus as claimed in claim 11, in which: said support means extends across near the reverse surface of the casting belt; and said series of heat sensing detectors are mounted on said support means and are located at spaced positions across the width of the casting belt near the casting region for monitoring the condition of the belt coating as the molten metal is being cast.

24. Apparatus as claimed in claim 11, wherein said machine is a twin-belt casting machine having an upper and a lower casting belt, and in which: at least two series of heat sensing detectors are included; said support means being associated with both belts and holding a first series of said detectors in contact with the moving, reverse, liquid-cooled surface of the lower belt near the casting region; and said support holding a second series of said detectors in contact with the moving, reverse, liquid-cooled surface of the upper belt near the casting region, whereby the operating condition of both casting belts is monitored as the molten metal is being cast.