Title of Invention

AN APPARATUS AND METHOD FOR DETERMINING THE PERCENTAGE OF CARBON EQUIVALENT, CARBON AND SILICON IN LIQUID FERROUS METAL

Abstract

The present invention relates to an apparatus and method for determining the percentage of Carbon Equivalent, Carbon and Silicon in liquid ferrous metal using embedded software. The apparatus of the present invention comprises of refractory cup structure(2), cavity(1), thermocouple wire(4), quartz tube(3), base(6), tellurium(5), holer(7), compensating cable(9), electronic device(8). The method of present invention comprises steps of a. Pouring of sample om refractory cup. b. Recording maximum temperature of the sample and allowing it to cool to solidification temperature. c. Determination of liquidus temperature, this temperature being inversely proportional gives percentage of carbon equivalent using algorithm. d. determination of solidus temperature using algorithm. e. the determination of percentage of carbon and silicon using embedded software based on algorithm. The present invention relates to the detection of the composition of liquid ferrous metal in a much quicker time using refractory cups and embedded software.

Full Text

FORM 2 THE PATENT ACT 1970 & The Patents Rules, 2003 PROVISIONAL / COMPLETE SPECIFICATION (See section 10 and rule 13) 1. TITLE OF THE INVENTION :An apparatus and method for determining the percentage of Carbon Equivalent, Carbon and Silicon in liquid ferrous metal. 2. APPLICANT(S)(a) NAME : 1. KAKATKAR ANANT KASHINATH2. KELKAR SATISH SHASHIKANT(b) NATIONALITY: Indian Nationals(c) ADDRESS : S.No.676, Pooja Apartment, Gruhkalp Society, Near Sugandha Lawn, Bibwewadi, PUNE- 411037. Maharashtra State, India. 3. PREAMBLE TO THE DESCRIPTION PROVISIONAL The following specification describes the invention. COMPLETEThe following specification particularly describes the invention and the manner in which it is to be performed. 4. 'DESCRIPTION (Description starts from page 2)n page 2) 5. CLAIMS: Given on a separate sheet 6. DATE AND SIGNATURE: Given at the end of last page of specification. 7. ABSTRACT OF THE INVENTION: Given on a separate sheet 1 The present invention relates to an apparatus and method for determining the percentage of Carbon Equivalent, Carbon and Silicon in liquid ferrous metal using embedded software. More particularly, the present invention relates to the detection of the composition of liquid ferrous metal in a much quicker time using refractory cups and embedded software. Background and Prior Art: Existing thermal analysis for detection of percentage of carbon equivalent, carbon and silicon requires about 180 seconds and consumes about 200- 325 grams of metal. Thermal analysis involves measurement and analysis of cooling pattern of the liquid metal, under controlled conditions. When liquid metal is poured in a cup, the maximum temperature as recorded by the cup is stored and further slow cooling is scanned. During cooling, when first nucleus solidifies , it gives away its kinetic energy, a thermal arrest is seen, which is metallurgically called as liquidus temperature (TL). This temperature being inversely proportional to the percentage of carbon equivalent (CE), helps in determining the %CE value. On further cooling, with the help of tellurium coating at the base of the cup, the sample is chilled and converted into white iron, instead of grey. This gives the solidification temperature (TS). The detection of TL and TS helps in detecting the percentage of Carbon and silicon. The existing cups used are round or square in shape such that 225- 325 grams of liquid metal can be accommodated for testing. Tellurium is pasted at the bottom of the cup or is coated all over the inner surface of the cup. The thermocouple wire used for measuring the temperature is a thick K type (CR-AL) wire of 22 S WG. US patent 3404570 discloses the method and apparatus for determining the concentration of a silicon in a sample of an electrically conductive material by measuring in a poured sample of the material cooling in a manner such that a temperature gradient exists across the sample, the temperature and a thermocouple force produced with the sample at each of two points in the sample spaced apart in the direction of the temperature 2 gradient. The magnitude of the difference between the electromotive forces at a predetermined temperature difference between the points is representative of the concentration of the constituent. However this method is complex and time consuming. US Patent No.3546921 discloses a method of producing an initial thermal arrest in the cooling curve of a molten sample of hypereutectic cast iron by addition of carbide stabilizers as Bi, B, Ce etc. are invented to get consistent discernible thermal arrest. However this method applies only for determination of only Carbon Equivalent by determination of Liquidus temperature only. This invention does not determine % Carbon and % Silicon in the metal. US Patent No.4059996 sets forth an improvement over the other by disclosing a blob of material in contact with the bottom wall of a cavity. The blob of material includes a carbide formation promoting material and preferably mixed with a material for evolving hydrogen. The refractory material aids in preventing the carbide formation promoting material from being burned up quickly and mixing too quickly with the molten metal. The hydrogen thus evolved is used to generate turbulence in metal that help carbide forming material to reach to every corner of cup and thus achieve formation of carbides all over the cup. The problem with this method is due to turbulence, the temperature drop is observed while filling the cup and cup filling is a skilled job. A stop and repeat pouring practice has to be followed to stop the boiling metal from coming out of the cup. All this is aimed at having uniform spreading of chilling agents throughout the cup. US Patent No. 4515485 also describe the improvement in U.S Patent No.4059996 for mixing of chilling agents through out the cup by using evolved hydrogen in a better controlled fashion. However it does not completely solve the problems associated with boiling and spilling of metal due to generation of hydrogen. 3 US Patent No. 4274284 describe a method to improve response time of Cromel Alumel thermocouple that is used to measure temperature of the cup. High response time is very essential for accurate measurement of thermal arrests as described therein. The thermocouple is under constant thermal stress till analysis is complete. This necessitates the use of thicker gauge causing response time and higher cost of wire and hence measurement. The gauge of the wire is more to withstand thermal stress as time requires for measurement is large. However, the thermocouple remains exposed to liquid metal and thus the metal contaminates the thermocouple hampering accuracy. US Patent No.6739750 provides a sampling vessel for thermal analysis of molten metal by reducing the time required with the help of probe type sampling vessel. The volume of the vessel is decided by the limitation in measurement accuracy of cooling rate. The cooling rate is required to be closer to (0 to - 0.02 as mentioned in the figure 3 B). In the said process the conventional diameter of around 30mm was reduced to around 20 mm and conventional depth of 50 mm was reduced to 36 mm or more. The use of this technique involves the use of costlier probe type sample having a limitation of minimum depth of 36 mm of cavity. US Patent No.5720553 describe the use of metallic inserts, instead of chilling agents, to act as a heat sink thereby promoting white solidification. However, the cost of measurement is high and technique involves immersion type of sampling which is not preferred for measurement everywhere. Drawbacks of Prior Art: 1. The metal solidifies in the patches of grey and white iron which hampers accuracy of the testing to a great extent. 2. The pouring temperature of the metal is very high. It burns off some amount of tellurium thereby affecting quality of test. 4 3. The thermocouple is under constant thermal stress till analysis is complete. 4. The metal is held in the furnace for longer time which results in loss of electricity/power and deteriorates the quality of metal. 5. The thermal analysis requires more time. 6. The quantity of metal required for analysis is more. 7. The quantity of chilling agent required is more. Summary of the Present Invention: The main object of the present invention is to provide; A) A method using refractory cup made from resin coated sand having capacity of 50 to 180gm instead of prior art cup which needs quantity of 200-325 gm. B) An embedded software for determination of percentage of carbon, silicon and carbon equivalent. Another object of the present invention is to increase the cooling rate by reducing the size of the resin coated cups. Lesser the volume, higher is the surface area to weight ratio and hence higher cooling rate is achieved. Still further object of the present invention is to achieve balance in the pouring temperature such that temperature and time required is available for mixing of chilling agents and at the same time maximum cooling rate is achieved. The purpose of the present invention is to reduce time needed for chilling material to mix at every corner of the cup in short time by reducing the distance of edges from centre of the cup by reducing the dimensions of the cup. 5 The aim of the present invention is to save time i.e. 50 to 80 seconds as against prior art, which needs 180 seconds and to save metal taken in the cavity for thermal analysis. Advantages of the Present Invention: 1. The metal solidifies into white iron as cooling rate is increased by reducing size of the cup and thereby reducing volume of the liquid metal which helps in accuracy of the testing. 2. The stress on the thermocouple last for a lesser time as time required for analysis is reduced due to faster cooling rate. 3. The time required for chilling material (tellurium) to mix at every corner of the cup is reduced as dimensions of the cup are changed. 4. The metal is held in furnace for shorter duration thereby saving electricity/power and helps in maintaining the quality of metal. 5. The quantity of metal required for analysis is less and thereby decrease in wastage of metal. 6. The quantity of chilling agents to convert gray iron to white iron is reduced. 7. The present invention thus provides convenient and rapid method for thermal analysis of a liquid ferrous metal. Description of the Present Invention: According to the present invention for thermal analysis of a liquid ferrous metal, there is provided an apparatus and method for determining the concentration of a 6 constituent in a liquid ferrous metal. More particularly present invention relates to a method and apparatus for determination of percentage of Carbon, Silicon and Carbon equivalent using embedded software. Apparatus: The apparatus of the present invention is illustrated in figure 1 of the accompanying drawing. The apparatus of the present invention comprises of well or mould or refractory cup structured), cavity(l), thermocouple wire(4), quartz tube(3), base(6), tellurium(5), holder(7), compensating cable(9), electronic device(8); The refractory cup structure or mould(2) is made from resin coated sand. The sand withstands high temperature of 1050 deg C to 1400 deg C as it is refractory in nature. The diameter and height of the cup structure(2) is around 20 to 40 mm and 10 to 25 mm respectively such that the weight of the metal in the cup is about 50 to 180 gm. The K type (CR-AL) 22 to 24 swg thermocouple wire(4) is used for measuring the temperature. Quartz tube shell(3) is fitted horizontally in the cup structured) such that it covers CR-AL wire(4). The quartz tube(3) avoid contact of liquid ferrous metal and thermocouple wire(4) and eliminate possibility of contamination. The quartz tube(3) is sealed with refractory agents so that there is no leakage from hole of cup(2). Chilling agents such as Bismuth, Boron, Cerium, Lead, Magnesium and Tellurium (5) are mixed with refractory binders is pasted at the bottom of the cup as chilling agent. The quantity of chilling agents used is 0.20 to 0.50 gm. (0.2 to 0.6% by weight). The refractory cup(2) has a suitable base(6) so as to fit it to the holder( 7 ). This holder then carries signal to the electronic device (8) via compensating cable( 9 ) for further analysis of percentage of Carbon, Silicon and Carbon equivalent. 7 An electronic device(8) capable of sensing thermal arrest points at high cooling rates is connected to the holder(7) through a compensating cable (9). Method: The liquid ferrous metal sample is poured in a cavity (1) of cup(2). The maximum temperature as recorded by the cup(2) is stored in the electronic device (8) and further cooling is scanned. The heat liberated when austenite starts to precipitate produces an isothermal arrest on the cooling curve. During solidification in the cup, latent heat is given out. Due to the effect of natural cooling and liberation of latent heat, a thermal equilibrium is reached and a thermal arrest is obtained. This temperature is called as Liquidus temperature (TL) . The arrest found, according to this invention is relatively weak due to faster cooling rate. This weak arrest is due to lower weight of sample and hence lower latent heat available to arrest temperature. The liquidus temperature being inversely proportional to the % carbon equivalent (CE), determine the % CE value empirically. The sample gets chilled with the help of chilling agents(5) coating at the bottom of the cup(2) from inside the cavity and the sample converted into white iron. When all the liquid metal solidifies one more thermal arrest is obtained. This temperature is called Solidus temperature (TS). The time required for analysis to complete is about 50 to 80 seconds. The detection of TL and TS is used for detecting the % Carbon Equivalent, % Carbon and % Silicon. This detection is possible if metal is converted in form of white iron suitably using coating of chilling agents at the bottom of the cup cavity. The embedded software accurately measures the faster cooling rates resulting due to the lower quantity of the sample under test. The algorithm of embedded software is given below 8 1. Store all the points of cooling process in an array. 2. Apply a software filter to fit a smooth curve for the cooling process. Interpolate the intermediate points on the smoothened curve. 3. Find the instantaneous cooling rate (1st derivative ) at each point of the smoothened cooling curve and store the cooling rate values in another array. 4. Apply a software filter to fit a smooth curve for the 1st derivative graph. 5. Find the 2nd derivative at each point of the smoothened 1st derivative curve and store the 2nd derivative values in another array. 6. Apply a software filter to fit a smooth curve for the 2nd derivative graph. 7. Find the 3rd derivative at each point of the smoothened 2n derivative curve and store the 3 rd derivative values in another array. 8. Find the maxima, minima and zero crossover points of cooling rate, 1st and 2nd derivative curves. 9. Find Maximum pouring temperature, liquidus temperature and solidus temperaure using these points. Liquidus and solidus point detection: When iron containing Carbon and silicon solidify, it does so over the range of temperature instead of solidifying at a particular freezing point. When metal is poured in the cup, the electronic device senses the maximum temperature. When metal is allowed to cool, initially it starts cooling at maximum cooling rate. When the temperature reaches the solidification temperature, few molecules start to solidify to precipitate austenite and thus give out latent heat of solidification. The resultant of natural cooling of metal and evolution of latent heat reduce the cooling rate of solidifying metal. Depending upon the quantity of latent heat available with the solidifying metal, the cooling rate start falling down, reach to a minimum level and start rising again. The temperature of lowest achieved cooling rate is the liquidus temperature. Since the readings are stored as time Vs temperature, the first derivative of these points is cooling rate and the second derivative is rate of change of cooling rate. Therefore when the second derivative pass through zero. The minima on the cooling rate curve is obtained. Corresponding temperature is the liquidus temperature. With the same principle the solidus temperature is found. When metal cool further, it 9 reaches a temperature where the metal is completely solid. It again give out heat and the cooling rate drop again. This change in cooling rate is sensed and latched as solidus temperature. Using algorithm, cooling rate from 0 to 3 deg C/sec can be measured, handled, analysed and used by electronic device for detecting Liquidus and solidus temperatures. 10. Find corresponding value of %Carbon Equivalent Using liquidus temperature and display its value on the electronic device. 11. Find corresponding value of %Carbon and % Silicon liquidus and solidus temperature and display values on the electronic device. The innovation in this algorithm essentially lies in step 2, where a software filter is applied and a smooth curve fit is generated. This algorithm arrests the points on the curve after a few seconds delay as the filtering process is involved but at the same time it is more precise when working with higher cooling rates. The algorithm detects Liquidus temperature and solidus temperatures at the cooling rate of 3 deg C / sec. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or matter. The embodiments of the invention as described above and the method disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention; which is defined by the scope of the following claims. 10 WE CLAIM: 1. An apparatus for determining the percentage of Carbon Equivalent, Carbon and Silicon in liquid ferrous metal comprising of refractory cup structure or mould or well(2); cavity(l); thermocouple wire(4); quartz tube(3); base(6); Chilling agents (5), holder(7), compensating cable(9), electronic device(8); The refractory cup structure(2) is made up of sand coated with resin; the diameter and height of the said cup structure is around 20 to 40 mm and 10 to 25 mm respectively; the cavity(l) is such that weight of the liquid metal or sample is about 50 to 180 gm; the K type (CR-AL) 22 to 24 SWG thermocouple wire(4) is used for measuring the temperature; quartz tube shell(3) is fitted horizontally in the said cup structure(2) such that it covers said CR-AL wire(4); the said quartz tube(3) avoids contact of said liquid ferrous metal and said thermocouple wire(4) and eliminates possibility of contamination; the said quartz tube(3) is sealed with refractory agents so that there is no leakage from hole of the said cup structure(2); Chilling agents (5) 0.20 to 0.50 gm mixed with refractory binders is pasted at the bottom of the said cup; the said cup(2) has a suitable base(6) so as to fit it to the holder(7).; this said holder(7). then carry signal to the electronic device (8) via compensating cable (9) for further analysis of percentage of Carbon equivalent, Carbon and Silicon. 2. A method using apparatus as claimed in claim 1 for determining the percentage of Carbon equivalent, Carbon and Silicon in a liquid ferrous metal using embedded software comprising steps of, a Pouring of sample in resin coated cup; b. Recording maximum temperature of the sample and allowing it to cool to solidification temperature; c. Determination of liquidus temperature; this temperature being inversely proportional gives percentage of carbon equivalent using algorithm; d. determination of solidus temperature using algorithm; e. the determination of percentage of carbon and silicon using embedded software based on 11 algorithm given below; 1. Store all the points of cooling process in an array; 2. Apply a software filter to fit a smooth curve for the cooling process. Interpolate the intermediate points on the smoothened curve; 3. Find the instantaneous cooling rate (1st derivative ) at each point of the smoothened cooling curve and store the cooling rate values in another array; 4. Apply a software filter to fit a smooth curve for the 1st derivative graph; 5. Find the 2nd derivative at each point of the smoothened 1st derivative curve and store the 2nd derivative values in another array; 6. Apply a software filter to fit a smooth curve for the 2nd derivative graph; 7. Find the 3rd derivative at each point of the smoothened 2nd derivative curve and store the 3rd derivative values in another array; 8. Find the maxima, minima and zero crossover points of cooling rate, 1st and 2nd derivative curves; 9. Find Maximum pouring temperature, liquidus temperature and solidus temperaure using these points; Liquidus and soildus point detection: When iron containing Carbon and silicon solidify, it does so over the range of temperature instead of solidifying at a particular freezing point; when metal is poured in the cup, the electronic device senses the maximum temperature; when metal is allowed to cool, initially it starts cooling at maximum cooling rate; when the temperature reaches the solidification temperature, few molecules start to solidify to precipitate austenite and thus give out latent heat of solidification; the resultant of natural cooling of metal and evoluion of latent heat reduce the cooling rate of solidifying metal; depending upon the quantity of latent heat available with the solidifying metal, the cooling rate start falling down, reach to a minimum level and start rising again; the temperature of lowest achieved cooling rate is the liquidus temperature; since the readings are stored as time Vs temperature, the first derivative of these points is cooling rate and the second derivative is rate of change of cooling rate; therefore when the second derivative pass through zero, the minima on the cooling rate curve is obtained; corresponding temperature is the 12 liquidus temperature; With the same principle the solidus temperature is found; When metal cools further, it reaches a temperature where the metal is completely solid; it again gives out heat and the cooling rate drop again; this change in cooling rate is sensed and latched as solidus temperature; Using algorithm, cooling rate from 0 to3 deg C/sec can be measured, handled, analysed and used by electronic device for detecting Liquidus and solidus temperatures; l0.Find corresponding value of %Carbon Equivalent Using liquidus temperature and display its value on the electronic device; 11 .Find corresponding value of %Carbon and % Silicon liquidus and solidus temperature and display values on the electronic device. 3. An apparatus as claimed in claim 1 where the cup structure is polygonal. 4. An apparatus as claimed in claim 1 wherein instead of tellurium other chilling agents e.g. Bismuth, Boron, Cerium, Lead, and Magnesium or alike can be used as an alternative. 5. An apparatus as claimed in claim 1 wherein instead of (CR-AL) 22 or 24 SWG thermocouple other thermocouple capable of measurement in the range of 1050 to 1400 deg C- can be used as an alternative. 6. An apparatus as claimed in claim 1 wherein the time of measuring percentage of Carbon Equivalent, Carbon and Silicon is from 50 to 80 seconds. 7. An apparatus and method as claimed in claim 1 to 6 substantially as herein before described with reference to and as shown in the accompanying drawing and specification. Dated this 28th of September, 2006. K.A.JOSHI AGENT FOR THE APPLICANT. 13 Abstract The present invention relates to an apparatus and method for determining the percentage of Carbon Equivalent, Carbon and Silicon in liquid ferrous metal using embedded software. The apparatus of the present invention comprises of refractory cup structure(2), cavity(l), thermocouple wire(4), quartz tube(3), base(6), tellurium(5), holder(7), compensating cable(9), electronic device(8). The method of present invention comprises steps of a. Pouring of sample in refractory cup. b. Recording maximum temperature of the sample and allowing it to cool to solidification temperature. c. Determination of liquidus temperature, this temperature being inversely proportional gives percentage of carbon equivalent using algorithm. d. determination of solidus temperature using algorithm. e. the determination of percentage of carbon and silicon using embedded software based on algorithm. The present invention relates to the detection of the composition of liquid ferrous metal in a much quicker time using refractory cups and embedded software.

Documents:

1584-mum-2006-abstract(11-7-2007).doc

1584-mum-2006-abstract(11-7-2007).pdf

1584-mum-2006-abstract.doc

1584-mum-2006-abstract.pdf

1584-mum-2006-cancelled pages(11-7-2007).pdf

1584-mum-2006-claims(granted)-(11-7-2007).doc

1584-mum-2006-claims(granted)-(11-7-2007).pdf

1584-mum-2006-claims.doc

1584-mum-2006-claims.pdf

1584-mum-2006-correspondance-received-ver-091006.pdf

1584-mum-2006-correspondance-received-ver-290906.pdf

1584-mum-2006-correspondence(7-3-2008).pdf

1584-mum-2006-correspondence(ipo)-(31-7-2008).pdf

1584-mum-2006-description (complete).pdf

1584-mum-2006-drawing(11-7-2007).pdf

1584-mum-2006-drawings.pdf

1584-mum-2006-form 1(29-9-2006).pdf

1584-mum-2006-form 18(27-12-2006).pdf

1584-mum-2006-form 2(granted)-(11-7-2007).doc

1584-mum-2006-form 2(granted)-(11-7-2007).pdf

1584-mum-2006-form 3(1-3-2008).pdf

1584-mum-2006-form 3(28-9-2006).pdf

1584-mum-2006-form 9(10-10-2006).pdf

1584-mum-2006-form-1.pdf

1584-mum-2006-form-2.doc

1584-mum-2006-form-2.pdf

1584-mum-2006-form-26.pdf

1584-mum-2006-form-3.pdf

1584-mum-2006-form-9.pdf

1584-mum-2006-power of authority(18-9-2006).pdf

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