DESC:FIELD
The present disclosure relates to the field of material science.
DEFINITIONS
As used in the present disclosure, the following term is generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicate otherwise.
The expression ‘quenching’ used hereinafter in this specification refers to, but is not limited to, rapid cooling of a heated component or workpiece in water, oil, gas or other coolants, often but not always, intended to obtain certain material properties such as hardness, crystal grain structure and the like.
The expression ‘vacuum furnace’ used hereinafter in this specification refers to, but is not limited to, a type of furnace in which vacuum is maintained, i.e., air and other oxidative and contaminating gases are removed from around the workpiece before carrying out a process such as annealing, brazing, sintering and heat treatment.
The expression ‘volume percentage’ used hereinafter in this specification refers to, but is not limited to, the ratio of volume of a component of a mixture of fluids to the total volume of the mixture of fluids expressed in percentage.
The expression ‘ratio regulator’ used hereinafter in this specification refers to, but is not limited to, a device which is configured to maintain a precise and constant ratio of supply volume of two gases in a mixture, such as between a gas and air. Typically, the inlet pressure to the ratio regulator is specified. The supply volume ratio of gases is maintained irrespective of the inlet pressure.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Quenching is a process of rapidly cooling heated components. Particularly, the heated components having a temperature in the range of 810°C to 910°C (austenitizing temperature) are cooled to bring about martensitic transformation (phase transformation) in quenched components (for example - steels) and improve mechanical properties such as core strength and hardness of the quenched components.
Conventionally, oil quenching or high pressure gas quenching can be used for cooling heated components. In the case of oil quenching, the efficiency of cooling depends on the oil type, oil temperature and agitation of the oil. However, the rate of cooling in oil quenching is significantly high due to which quenched components are distorted substantially while agitating the oil. Typically, during oil quenching, the heated components are subjected to thermal shock which increases the strength of quenched components, but this causes the quenched components to distort. Moreover, surface cleaning is essential in oil quenching, thereby increasing the cost and time consumption of the entire process.
In the case of high pressure gas quenching, the efficiency of cooling is dependent on the type of gas for example - helium, argon and nitrogen, pressure of the gas, quenching pressure and gas circulation speed, i.e., turbine speed. The heated components are cooled in a controlled manner and due to this; the distortion in quenched components is less as compared to that observed in oil quenching. However, the strength of the quenched components is less as compared to that achieved in the case of oil quenching. The strength of the quenched components can be improved by using components of a higher grade, which in turn increases the cost of components.
Hydrogen has the highest heat transfer coefficient in W/m2K amongst conventional gases used for pressurized gas quenching, more than that of helium, nitrogen, argon. The lighter the gas molecule, the higher is the heat transfer coefficient. However, use of hydrogen for quenching is limited by its high combustibility.
There is, therefore, felt a need of an apparatus and a method for quenching heated components that obviate the above mentioned drawbacks.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide an apparatus and a method for quenching heated components.
Another object of the present disclosure is to provide an apparatus and a method for quenching heated components so as to increase the core strength of the quenched components.
Yet another object of the present disclosure is to provide an apparatus and a method for quenching heated components with minimal distortion of quenched components.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure envisages an apparatus for quenching a heated component. The apparatus comprises a first reservoir, a second reservoir, a high-pressure chamber and a ratio regulator.
The first reservoir is configured to store a first gas at a pressure greater than a predetermined pressure. The predetermined pressure is higher than atmospheric pressure. The second reservoir is configured to store a second gas at a pressure greater than a predetermined pressure. The predetermined pressure is higher than atmospheric pressure. In an embodiment, the first gas is selected from the group consisting of helium, nitrogen and argon and any combination thereof, and the second gas is hydrogen.
The high-pressure chamber is configured for receiving gases. The chamber includes means for receiving the heated component for quenching. The high-pressure chamber is a sealable chamber and is part of a vacuum furnace. The chamber is configured to receive gases for quenching the heated component for quenching. Typically, the high-pressure chamber includes a door, which can be sealed air-tight, for introducing the heated component into the chamber, and a tray or other support means on which the heated component can be placed for quenching.
The ratio regulator is fitted between the reservoirs and the chamber. The ratio regulator is connected to the outlets of the first reservoir and the second reservoir and the inlet of the chamber. The ratio regulator is configured to facilitate formation of a mixture of the first gas and the second gas. The ratio regulator is also configured to facilitate control of the volume percentage of the second gas in a mixture of the first gas and the second gas. In an embodiment, the ratio regulator is a ratio control valve.
The mixture of the first gas and the second gas is circulated over the heated component at the predetermined pressure to accomplish quenching of the heated component. In an embodiment, the apparatus includes a turbine which is configured to receive the mixture of the first gas and the second gas and is configured to circulate the mixture over the surface of the heated component in the high-pressure chamber for quenching the heated component.
In an embodiment, a high-pressure gas conduit connects the ratio regulator to the high-pressure chamber.
In another embodiment, the predetermined pressure ranges from 18 bar to 22 bar.
In yet another embodiment, the volume percentage of the second gas in the mixture of the first gas and the second gas ranges from 0% to 35%.
In still embodiment, the apparatus includes a heat exchanger which cooperates with the high-pressure chamber and is configured to cool the mixture of the first gas and the second gas.
Preferably, the ratio regulator is controlled to regulate volume percentage of gases in the mixture based on one of desired cooling speed, desired core hardness or desired strength of the heated component in terms of bending strength, tensile strength, compression, sheer strength or torsional strength.

DESCRIPTION OF RELATED DRAWING
The present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates a schematic view of an apparatus for quenching heated components, in accordance with an embodiment of the present disclosure;
Figure 2 illustrates a graph illustrating the rate of quenching using nitrogen, oil and a mixture of nitrogen and hydrogen.
LIST OF REFERENCE NUMERALS
100 - Apparatus
1 - (First reservoir) Nitrogen buffer tank
2 - (Second reservoir) Hydrogen buffer tank
3 - (Ratio regulator) Ratio control valve
4 - High pressure gas conduit
5 - High pressure chamber
6 - Motor
6a - Turbine
7 - Heat exchanger
8 - Heated component
Curve 9 - Nitrogen cooling curve
Curve 10 - Hydrogen cooling curve
Curve 11 - Nitrogen and hydrogen mixture cooling curve
DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
When an element is referred to as being "mounted on," “engaged to,” "connected to," or "coupled to" another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Terms such as “inner,” “outer,” "beneath," "below," "lower," "above," "upper," and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.
As described herein above, there are certain drawbacks associated with conventional methods such as oil quenching and high pressure gas quenching, for example – in case of oil quenching, there is distortion of quenched components and in case of high pressure gas quenching, core strength of quenched components is not improved.
The present disclosure, therefore, envisages an apparatus and a method for quenching heated components and obviating the above mentioned drawbacks.
A preferred embodiment of the apparatus 100 is described with reference to Figure 1. The apparatus 100 comprises a first reservoir 1 which is a nitrogen buffer tank, a second reservoir 2 which is a hydrogen buffer tank, a ratio regulator 3 which is a ratio control valve, a high pressure gas conduit 4, a high-pressure chamber 5 (of a vacuum furnace), a motor 6 and a turbine 6a and a heat exchanger 7.
The high-pressure chamber 5 is configured for receiving gases. The chamber 5 includes means for receiving the heated component for quenching. The chamber 5 is a sealable chamber and is part of a vacuum furnace. The chamber 5 is configured to receive gases for quenching the heated component 8 for quenching. Typically, the high-pressure chamber 5 includes a door, which can be sealed air-tight, for introducing the heated component into the chamber, and a tray or other support means on which the heated component 8 can be placed for quenching.
The ratio regulator 4 is fitted between the reservoirs 1, 2 and the chamber 5. The ratio regulator 4 is connected to the outlets of the first reservoir 1 and the second reservoir 2 and the inlet of the chamber 5. The ratio regulator 4 is configured to facilitate formation of a mixture of the first gas and the second gas. The ratio regulator 4 is also configured to facilitate control of the volume percentage of the second gas in a mixture of the first gas and the second gas.
The method is described in the steps provided herein below with reference to apparatus 100.
Nitrogen from the nitrogen buffer tank 1 and hydrogen from the hydrogen buffer tank 2 are mixed with the help of the ratio control valve 3 to obtain a gaseous mixture of nitrogen and hydrogen. The amount of hydrogen and nitrogen in the gaseous mixture can be in the range of 5 vol% to 35 vol% and above 35 vol% respectively. Particularly, the amount of hydrogen and nitrogen in the gaseous mixture can be varied depending upon desired cooling rates rate (rate of change of temperature with respect to time) to be achieved. The pressure of the nitrogen buffer tank 1 and the hydrogen buffer tank 2 can be maintained at a pressure greater than quenching pressure (typically, 20 bar).
The gaseous mixture is pressurized to a non-limiting pressure of 20 bar. The pressurized gaseous mixture is allowed to pass through the high pressure gas conduit 4, and the gaseous mixture is circulated in the high-pressure quenching chamber 5 with the help of a turbine 6a coupled to the motor 6. Particularly, before circulating the pressurized gaseous mixture in the high-pressure quenching chamber 5, a heated component 8 is introduced into the high-pressure quenching chamber 5, typically through a door which can be sealed air-tight, and the air content from the high pressure quenching chamber 5 is removed beforehand (before introduction of heated component into the high pressure quenching chamber) to create vacuum therein, and the heated component 8 is placed on a tray or similar means for receiving the heated component 8. The door of the high-pressure quenching chamber 5 is closed after the removal of air content therefrom. In the high-pressure quenching chamber 5, the heated component 8 is quenched by the pressurized gaseous mixture to obtain a quenched component by contacting the heated component 8 with the pressurized gaseous mixture.
During the quenching of the heated component 8, the pressurized gaseous mixture gets heated. In order to re-circulate the pressurized gaseous mixture into the high-pressure quenching chamber 5, the pressurized gaseous mixture is allowed to pass through the heat exchanger 7 to cool the pressurized gaseous mixture.
The effect on rate of quenching or cooling of the heated component 8 using the pressurized gaseous mixture (a mixture of nitrogen and hydrogen at 20 bar pressure, represented by curve 11), nitrogen at 20 bar pressure (represented by curve 9) and oil (represented by curve 10) is depicted in Figure 2.
From Figure 2, it is evident that the cooling in case of the pressurized gaseous mixture comprising hydrogen as a constituent, as obtained according to the method claimed in the present disclosure, is better as compared to that of nitrogen alone. It is also evident that the cooling rate in case of the pressurized gaseous mixture, according to the present disclosure, is similar to that of oil quenching.
The apparatus and the method of the present disclosure facilitates in quenching heated components at cooling rates similar to that of oil quenching, to obtain quenched components with improved strength or core hardness with minimal distortion of the quenched components. Moreover, with the use of the gaseous mixture comprising hydrogen, the use of a high-cost gas such as helium is obviated.
TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of an apparatus and a method that makes use of a mixture of hydrogen and nitrogen, which:
• facilitates quenching of heated components to obtain quenched components with improved core strength and with minimal distortion of the quenched components;
• is capable of reducing need for using components of higher grade;
• has cooling rates better as compared to that of nitrogen;
• has cooling rates similar to that of oil quenching;
• obviates the use of high-cost gas such as helium;
• eliminates the process step of cleaning the surface of the component (required in case of oil quenching), thereby reducing the cost of the entire process and increasing the productivity as compared to that of oil quenching;
• eliminates the chances of oxidation during quenching, because hydrogen is a reducing agent; and
• facilitates in quenching of heated components to obtain quenched components with improved component life by approximately 70%, as compared to that of oil quenching, due to the absence of intergranular oxidation (IGO).
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

,CLAIMS:WE CLAIM:
1. An apparatus (100) for quenching a heated component (8), comprising:
• a first reservoir (1) configured to store a first gas at a pressure greater than a predetermined pressure, said pressure being higher than atmospheric pressure;
• a second reservoir (2) configured to store a second gas at a pressure greater than a predetermined pressure, said pressure being higher than atmospheric pressure;
• a high-pressure chamber (5) for receiving gases, said chamber including means for receiving said heated component (8) for quenching; and
• a ratio regulator (3) fitted between the reservoirs and said chamber, said ratio regulator (3) connected to the outlets of said first reservoir (1) and said second reservoir (2) and the inlet of said chamber (5), said ratio regulator (3) is configured to facilitate:
o formation of a mixture of said first gas and said second gas at said predetermined pressure; and
o control of the volume percentage of said second gas in a mixture of said first gas and said second gas;
characterized in that:
said mixture of said first gas and said second gas is circulated over said heated component (8) at said predetermined pressure to accomplish quenching of said heated component (8).
2. The apparatus (100) as claimed in claim 1, wherein said high-pressure chamber (5) is a sealable chamber and is part of a vacuum furnace and said chamber (5) is configured to receive gases for quenching said heated component (8) for quenching.
3. The apparatus (100) as claimed in claim 1, wherein a high-pressure gas conduit (4) connects said ratio regulator (3) with said high-pressure chamber (5).
4. The apparatus (100) as claimed in claim 1, which includes a turbine (6a) configured to receive said mixture of said first gas and said second gas and to circulate said mixture over the surface of said heated component (8) in said high-pressure chamber (5) for quenching said heated component (8).
5. The apparatus (100) as claimed in claim 1, wherein said first gas is selected from the group consisting of helium, nitrogen and argon and any combination thereof, and said second gas is hydrogen.
6. The apparatus (100) as claimed in claim 1, wherein said predetermined pressure ranges from 18 bar to 22 bar.
7. The apparatus (100) as claimed in claim 1, wherein the volume percentage of said second gas in said mixture of said first gas and said second gas ranges from 0% to 35%.
8. The apparatus (100) as claimed in claim 1, which includes a heat exchanger configured to cooperate with said high-pressure chamber (5) for cooling said mixture of said first gas and said second gas resident in said chamber (5).
9. The apparatus (100) as claimed in claim 1, wherein said ratio regulator (3) is a ratio control valve.