Title of Invention	"AN IMPROVED PROCESS FOR PRODUCING ANNULAR HEAT-TREATED CIRCULAR SLIDING AND ROLLING MACHINE PARTS LIKE WHEELS OF RAIWAY WAGONS AND LOCOMOTIVES"
Abstract	The invention provides an improved process for producing annular heat-treated circular sliding and rolling machine parts like wheels of railway v/agons and locomotives, comprising the steps in sequence : (a) heating a part in a rotating hearth furnace to a temperature of 800-850°C; (b) soaking the part completely at the said temperature; (c) placing the part by means of mobile charger on a turn table; (d) moving downward a cover/lid onto the turn table to enclose a water-spray ring and the heated part placed on the turn table by means of a pneumatic cylinder; (e) starting rotation of the turn table by an automatic device as soon as the cover/lid is brought in contact with the turn table; (f) starting the supply of water from an overhead tank at the specified pressure to the water-spray ring through two inlets by means of actuator valves automatically as soon as the rotation of the turn table commences; (g) stopping the supply of water to the water-spray ring automatically on the expiry of 220-260 seconds by actuation of a valve provided for the purpose; (h) flushing out the v/ater left in the water-spray ring with compressed air from a plant by automatically switching on the pressure control valves provided; (i) raising the cover/lid upward from the level of the turn table surface automatically by means of the pneumatic cylinders provided; (j) removing the heat-treated part from the turn table surface by means of a mobile charger provided; (k) allowing the heat-treated part to self-temper in natural air for 20 to 30 minutes by conduction of heat from its core region to its surface region; (l) tempering the heat-treated part in a rotary hearth tempering furnace for 60 to 90 minutes at 500-550°C; and (m) cooling the heat-treated and tempared part in natural air to ambient temperature.

Title of Invention

"AN IMPROVED PROCESS FOR PRODUCING ANNULAR HEAT-TREATED CIRCULAR SLIDING AND ROLLING MACHINE PARTS LIKE WHEELS OF RAIWAY WAGONS AND LOCOMOTIVES"

Abstract

The invention provides an improved process for producing annular heat-treated circular sliding and rolling machine parts like wheels of railway v/agons and locomotives, comprising the steps in sequence : (a) heating a part in a rotating hearth furnace to a temperature of 800-850°C; (b) soaking the part completely at the said temperature; (c) placing the part by means of mobile charger on a turn table; (d) moving downward a cover/lid onto the turn table to enclose a water-spray ring and the heated part placed on the turn table by means of a pneumatic cylinder; (e) starting rotation of the turn table by an automatic device as soon as the cover/lid is brought in contact with the turn table; (f) starting the supply of water from an overhead tank at the specified pressure to the water-spray ring through two inlets by means of actuator valves automatically as soon as the rotation of the turn table commences; (g) stopping the supply of water to the water-spray ring automatically on the expiry of 220-260 seconds by actuation of a valve provided for the purpose; (h) flushing out the v/ater left in the water-spray ring with compressed air from a plant by automatically switching on the pressure control valves provided; (i) raising the cover/lid upward from the level of the turn table surface automatically by means of the pneumatic cylinders provided; (j) removing the heat-treated part from the turn table surface by means of a mobile charger provided; (k) allowing the heat-treated part to self-temper in natural air for 20 to 30 minutes by conduction of heat from its core region to its surface region; (l) tempering the heat-treated part in a rotary hearth tempering furnace for 60 to 90 minutes at 500-550°C; and (m) cooling the heat-treated and tempared part in natural air to ambient temperature.

Full Text	The present invention relates to an improved process for producing annular heat-treated circular sliding and rolling machine parts like wheels of railway wagons and locomotives. The invention relates also to an improved system for annular heat-treatment of circular sliding and rolling machine parts like wheels of railway wagons as disclosed in Indian Patent Application No.912/Del/96 from which the present application has been divided out. The invention relates more particularly to a process for high-pressure spray-quenching of the rim of forged wheels of railway wagons and locomotives to achieve uniform hardness in the rim and a gradual reduction in hardness from the rim to the core of the wheel. The existing process for heat-treatment of the rim of wheels of railway wagons comprises the following steps :-(a) heating the wheel to a specified temperature for a specified period; (b) placing the wheel to be heat-treated on a stationary platform; and (c) applying quenching water around the rim of the wheel by means of a stationary water spraying ring, while wheel is allowed to rotate. The drawbacks of the existing process for heat-treatment of the rim of wheels of railway wagons are that the hardness produced in the wheel rim is low and not uniform and that the decrease in hardness from the rim to the core of the heat-treated wheel is not gradual, because of both the above-mentioned drawbacks the performance of the wheels is affected adversely. Distinguishing features of the invention with reference to prior art are:- 1. The present invention provides an improved process using a fully automatic means for controlling the various steps followed in sequence according to a preset programme. In prior art no such automation of steps, is provided. 2. The present invention provides flexibility to control flow rate, flow pattern, distance between nozzles and work piece and allows to heat- treat different types (having different diameter and mass) of railway wheels or other annular items. No such flexibility is provided in prior art. 3. Desired hardness at surface and inside as required is obtained by optimizing process parameters in the present invention. In proior art, such optimization is not provided. 4. The present invention provides a more reliable and accurate system than the prior art. 5. In the prior art process, the hardness of the rim and the hardness-gradient from the rim to the core of circular parts like wheels of railway wagons are not optimized by controlling automatically the speed of rotation of the circular parts and the duration of quenching to preset levels. In the invented process, the hardness of the rim and the hardness-gradient from the rim to the core of circular parts like wheels of railway wagons are optimized by controlling automatically the speed of rotation of the circular parts at 10 to 15 r.p.m., the duration of quenching at 220 to 260 seconds, and the pressure of the water spray at 2.5 to 3.5 Kg/cm2 6. In the process of prior art, the water used for quenching is allowed to be wasted. In the invented process, the water used for quenching is recycled to prevent wastage of water. The objective of the present invention is to provide an improved process for heat treatment of circular sliding and rolling machine parts, which is capable of producing high hardness as well as uniform hardness gradient from the rim to the core of the parts. Another objective is to provide an improved process using a fully automatic means for controlling the various steps followed in sequence according to a preset programme. Yet another objective is to provide an improved process which is suitable for hear-treating circular objects of different dimensions. A further objective is to provide a process using a means for recycling the water used for heat treatment of the parts. The improved process is carried out using a system which comprises the following accessories: - (i) a stationary circular tube for supplying quenching water, called water-spray ring, having a number of spray nozzles distributed at equal intervals along its internal periphery, all being directed towards its centre; (ii) a circular turntable for holding the parts to be heat-treated, mounted rotatably and co-axially with respect to the said stationary water-spray ring; (iii) a driving mechanism for rotating the turntable at a preset speed; (iv) a cover/lid for enclosing the water-spray ring and the parts placed on the turntable during the heat-treatment thereof by spraying quenching water from the ring, the cover/lid being movable in the axial direction of the water-spray ring and turntable by means of a pneumatic cylinder; (v) a pneumatic cylinder for causing the movement of the cover in the axial direction of the water-spray ring and of the turn table; (vi) a plant for supplying water from an overhead tank at a high pressure to the water-spray ring and pumping the used water back to overhead tank; (vii) a plant for supplying compressed air to the pneumatic cylinders for causing movement of the cover/lid to/from the turn table, to pneumatically controlled valves and to actuator operated valves used in the system; (viii) two infra-red pyrometers for measuring the temperature of heated parts placed on the turn table; and (ix) a control cubicle containing means for displaying the various operating conditions of the system viz. temperature of the parts to be heat-treated, pressure and flow rate of water supplied to the water-spray ring as well as a computer for automatically controlling and synchronising the operation of different functional units of the system according to a preset programme. Thus the invention provides an improved process for producing annular heat-treated circular sliding and rolling machine parts like wheels of railway wagons and locomotives, using the system as described herein, characterised in that the process comprises the following steps in sequence : (a) heating part in a rotating hearth furnace to an elevated temperature of 800 - 850°C, soaking the part completely at the said elevated temperature, placing the part by means of a mobile charger on turn table, moving downward cover/lid onto the turn table to enclose water-spray ring and the heated part placed on the turn table by means of pneumatic cylinder and starting rotation of the turn table automatically as soon as the cover/lid comes to be in contact with the turn table; (b) starting the supply of high pressure water from overhand tank at a pressure of 2.5 - 3.5 kg/cm2 to ring through two inlets by means of actuator valves automatically as soon as the speed of rotation of the turn table increases to 10 - 15 r.p.m.; (c) stopping the supply of high-pressure water to the ring automatically on expiry of a quenching duration of 220 - 260 seconds by actuating a valve provided for the purpose; (d) flushing out the water left in the water-spray ring with compressed air from plant by automatically switching on pressure control valves, raising the cover/lid upward from the level of the turn table surface automatically by means of pneumatic cylinders, removing the heat-treated part from the turn table surface by means of a mobile charger at a temperature of 500 - 600°C; and (e) allowing the heat-treated part to self-temper in natural air by conduction of heat from its core region to its surface region for a duration of 120 to 180 minutes. An embodiment of the system used for the invented process is described with reference to the accompanying drawings in which - Figure 1 is a sketch of the system comprising sources of high pressure water and compressed air supplies, heat-treatment unit, pressure control valves, pneumatic cylinders, actuator operated valves, control cubicle; Figure 2 shows the sectional diagram of the water-spray ring; Figure 3 shows the sectional elevation of the heat-treatment unit containing water-spray ring, turn table with the part to be heat-treated placed thereon and driving mechanism for rotating the turn table. Referring to Fig. 1, water from the water main (M) is stored in the overhead tank (H), typically of capacity 23,000 litre, from which it is supplied through a number of pressure control valves (PCV), two filters (F1, F2), two pumps (P1, P2) for raising the pressure of water to a high level i.e. 5 Kg/Cm , which is supplied to the water-spray ring (R) having a number of nozzles (N) through pressure control valves (PCV) and actuator operated valves (AOV1, AOV2, AOV3). The excess water at high pressure is returned to tank (H) through actuator operated valve (AOV4). Two infra-red pyrometers (PRM1, PRM2) are provided for measuring the temperature of the heated part placed on turn table (T) enclosed by cover/lid (C). The cover/lid (C) is movable by means of pneumatic cylinder (PNC1) and the part to be heat-treated is placed on the turn table by means of mobile charger and removed from the turn table on completion of the heat treatment by means of mobile charger. Control cubicle (CC) is supplied with parameters for controlling the operation of the system such as (i) dimensional particulars of the part to be heat-treated, (ii) temperature of the part, (iii) duration of high pressure water supply, (iv) pressure of water supply, (v) flow rate of water supply and (vi) rotational speed of the turn table. The plant for supplying compressed air (PAS) supplies compressed air to pressure control valves (PCV), pneumatic cylinders (PNC1) and actuator operated valves (AOV1, AOV2, AOV3, AOV4). The used water is collected in sump (SP) and fed back into tank (H). Referring to Fig. 2, the circular water-spray ring (R) is of internal diameter 1525 mm and made of a tube of internal diameter 38mm. The ring is provided with 16 nozzles (N) at equal intervals along its inner periphery and directed towards its centre. Each nozzle is of length 152 mm/254 mm, having one nipple and two fixing sockets (S), each of internal diameter 18 mm. Two inlets (I) are provided for supplying high pressure water into the ring, each inlet being of internal diameter 38 mm, Referring to Fig. 3, the table (T) is rotated by means of a driving mechanism comprising motor (M), gearbox (G) and flexible steel coupling (E). The part (P) to be heat-treated is placed on the turn table (T) with the rim of the part (P) being encircled by water-spray ring (R) which is supplied with high pressure water through two inlets (I) through actuator operated valves (AOV1, AOV2). The cover/lid (C) and part (P) are moved by means of pneumatic cylinders (PNC1) which are supplied with compressed air from an air cylinder (A) of internal diameter of 203 mm. Motor (M) and gearbox (G) are disposed with their horizontal axes at the floor level. Thus the invention provides an improved process for producing annular heat-treated circular sliding and rolling machine parts like wheels of railway wagons and locomotives, using the system as described herein, comprising the following steps in sequence : (a) heating part (P) in a rotary hearth furnace to a specified elevated temperature; (b) soaking the part completely at the said elevated temperature; (c) placing the part by means of mobile charger on turn table (T); (d) moving downward cover lid (C) onto the turn table to enclose water-spray ring (R) and the heated part placed on the turn table by means of mobile charger; (e) starting rotation of the turn table automatically as soon as the cover/lid comes to be in contact with the turn table; (f) starting the supply of high pressure water from overhand tank (H) at a specified pressure to water-spray ring (R) through two inlets (l) by means of actuator valves (AOV1, AOV2, AOV3) automatically as soon as the speed of rotation of the turn table increases to a preset limit; (g) stopping the supply of high-pressure water to the water-spray ring automatically on expiry of a preset quenching duration by actuation of a valve provided for the purpose; (h) flushing out the water left in the water-spray ring with compressed air from plant (PAS) by automatically switching on pressure control valves (PCV); (i) raising the cover/lid upward from the level of the turn table surface automatically by means of pneumatic cylinders (PNC1); (j) removing the heat-treated part at a given temperature from the turn table surface by means of mobile charger; (k) allowing the heat-treated part to self-temper in natural air for a given duration by conduction of heat from its core region to its surface region; characterised in that (a) the elevated temperature of the part to be heat- treated is 800-850°C; (b) high pressure water is supplied to the water-spray ring at a pressure of 2.5-3.5 kg/cm2; (c) the supply of water to the water-spray ring is started as soon as the speed of rotation of the turn table increases to a limit of 10-15 rpm; (d) the supply of high pressure water to the water-spray ring is stopped on expiry of a quenching duration of 220-260 seconds; (e) the heat-treated part is removed from the turn table surface for tempering at a temperature of 500-600°C; and (f) the heat-treated part is allowed to self-temper in natural air for a duration of 120 to 180 minutes. A number of locomotive wheels containing carbon 0.57-0.6796 and manganese 0.60-0.85%by weight were heat treated in a steel plant in the invented process under the conditions given in Table I. The aimed at and achieved properties in the heat-treated wheels are given in Table II. On an average 8 machine parts such as locomotive wheels can be heat-treated per hour in the invented process. Table I Conditions of Heat-treatment followed for locomotive wheels (Table Removed) Table II Properties of Heat-treated locomotive wheels (Table Removed) The invented process has a number of advantageous features over the existing process, such as, (i) variable rate of quenching during the heat treatment; (ii) rotation of the part during heat treatment, leading to uniform hardness along the rim of the part; (iii) quenching of the part under optimised flow rate and pressure of the quenching water, and optimised orientation and dimensions of the nozzles for spraying the quenching water leading to gradual reduction of hardness from the rim toihe core of the heat-treated machine parts; (iv) suitability for heat-treating machine parts of versalite dimensions; (v) minimised consumption of the quenching water; (vi) adjustable conditions for heat-treatment; and (vii) fully automised operations. We Claim :- 1. An improved process for producing annular heat-treated circular sliding and rolling machine parts like wheels of railway wagons and locomotives, using the system as described herein, characterised in that the process comprises the following steps in sequence : (a) heating part (P) in a rotating hearth furnace to an elevated temperature of 800 - 850°C, soaking the part completely at the said elevated temperature, placing the part by means of a mobile charger on turn table (T) , moving downward cover/lid (C) onto the turn table to enclose water-spray ring (R) and the heated part placed on the turn table by means of pneumatic cylinder (PNC1) and starting rotation of the turn table automatically as soon as the cover/lid comes to be in contact with the turn table; (b) starting the supply of high pressure water from overhand tank (H) at a pressure of 2.5 - 3.5 kg/cm2 to ring (R) through two inlets (I) by means of actuator valves (AOV1, AOV2, AOV3) automatically as soon as the speed of rotation of the turn table increases to 10 - 15 r.p.m.; (c) stopping the supply of high-pressure water to the ring automatically on expiry of a quenching duration of 220 - 260 seconds by actuating a valve provided for the purpose; (d) flushing out the water left in the water-spray ring with compressed air from plant (PAS) by automatically switching on pressure control valves (PCV), raising the cover/lid upward from the level of the turn table surface automatically by means of pneumatic cylincers (PNC1), removing the heat-treated part from the turn table surface by means of a mobile charger at a temperature of 500 - 600°C; and (e) allowing the heat-treated part to self-temper in natural air by conduction of heat from its core region to its surface region for a duration of 120 to 180 minutes. 2. The process as claimed in claim 1, wherein the part to be heat-treated is heated to an elevated temperature of 810-820°C, water is supplied to the water-spray ring at a pressure of 3kg/cm2 , the supply of water to the water-spray ring is started when the speed of rotation of the turn table attains a limit of 15 rpm, the supply of water to the water-spray ring is stopped on expiry of a quenching duration of 240 seconds, the heat-treated part is removed from the turn table surface for tempering at a temperature of 550°C and the heat-treated part is allowed to self-temper in natural air for a duration of 150 seconds. 3. An improved process for producing annular heat-treated circular sliding and rolling machine parts like wheels of railway wagons and locomotives, substantially as herein described with reference to the accompanying drawings.

Full Text

The present invention relates to an improved process for producing annular heat-treated circular sliding and rolling machine parts like wheels of railway wagons and locomotives.
The invention relates also to an improved system for annular heat-treatment of circular sliding and rolling machine parts like wheels of railway wagons as disclosed in Indian Patent Application No.912/Del/96 from which the present application has been divided out.
The invention relates more particularly to a process for high-pressure spray-quenching of the rim of forged wheels of railway wagons and locomotives to achieve uniform hardness in the rim and a gradual reduction in hardness from the rim to the core of the wheel.
The existing process for heat-treatment of the rim of wheels of railway wagons comprises the following steps :-(a) heating the wheel to a specified temperature for a specified period; (b) placing the wheel to be heat-treated on a stationary platform; and (c) applying quenching water around the rim of the wheel by means of a stationary water spraying ring, while wheel is allowed to rotate.
The drawbacks of the existing process for heat-treatment of the rim of wheels of railway wagons are that the hardness produced in the wheel rim is low and not uniform and that the decrease in hardness from the rim to the core of the heat-treated wheel is not gradual, because of both the above-mentioned drawbacks the performance of the wheels is affected adversely.

Distinguishing features of the invention with reference to prior art are:-
1. The present invention provides an improved process using a
fully automatic means for controlling the various steps followed in sequence
according to a preset programme. In prior art no such automation of steps, is
provided.
2. The present invention provides flexibility to control flow rate,
flow pattern, distance between nozzles and work piece and allows to heat-
treat different types (having different diameter and mass) of railway wheels
or other annular items. No such flexibility is provided in prior art.
3. Desired hardness at surface and inside as required is obtained
by optimizing process parameters in the present invention. In proior art, such
optimization is not provided.
4. The present invention provides a more reliable and accurate
system than the prior art.
5. In the prior art process, the hardness of the rim and the
hardness-gradient from the rim to the core of circular parts like wheels of
railway wagons are not optimized by controlling automatically the speed of
rotation of the circular parts and the duration of quenching to preset levels.
In the invented process, the hardness of the rim and the hardness-gradient from the rim to the core of circular parts like wheels of railway wagons are optimized by controlling automatically the speed of rotation of the circular parts at 10 to 15 r.p.m., the duration of quenching at 220 to 260 seconds, and the pressure of the water spray at 2.5 to 3.5 Kg/cm2
6. In the process of prior art, the water used for quenching is
allowed to be wasted.
In the invented process, the water used for quenching is recycled to prevent wastage of water.

The objective of the present invention is to provide an improved process for heat treatment of circular sliding and rolling machine parts, which is capable of producing high hardness as well as uniform hardness gradient from the rim to the core of the parts.
Another objective is to provide an improved process using a fully automatic means for controlling the various steps followed in sequence according to a preset programme.
Yet another objective is to provide an improved process which is suitable for hear-treating circular objects of different dimensions.
A further objective is to provide a process using a means for recycling the water used for heat treatment of the parts.
The improved process is carried out using a system which comprises the following accessories: -
(i) a stationary circular tube for supplying quenching
water, called water-spray ring, having a number of spray nozzles distributed at equal intervals along its internal periphery, all being directed towards its centre;
(ii) a circular turntable for holding the parts to be heat-treated, mounted rotatably and co-axially with respect to the said stationary water-spray ring;
(iii) a driving mechanism for rotating the turntable at a preset speed;
(iv) a cover/lid for enclosing the water-spray ring and the parts placed on the turntable during the heat-treatment thereof by spraying quenching water from the ring, the cover/lid being movable in the axial direction of the water-spray ring and turntable by means of a pneumatic cylinder;

(v) a pneumatic cylinder for causing the movement of the cover in the axial direction of the water-spray ring and of the turn table;
(vi) a plant for supplying water from an overhead tank at a high pressure to the water-spray ring and pumping the used water back to overhead tank;
(vii) a plant for supplying compressed air to the pneumatic cylinders for causing movement of the cover/lid to/from the turn table, to pneumatically controlled valves and to actuator operated valves used in the system;
(viii) two infra-red pyrometers for measuring the temperature of heated parts placed on the turn table; and
(ix) a control cubicle containing means for displaying the various operating conditions of the system viz. temperature of the parts to be heat-treated, pressure and flow rate of water supplied to the water-spray ring as well as a computer for automatically controlling and synchronising the operation of different functional units of the system according to a preset programme.
Thus the invention provides an improved process for producing annular heat-treated circular sliding and rolling machine parts like wheels of railway wagons and locomotives, using the system as described herein, characterised in that the process comprises the following steps in sequence :
(a) heating part in a rotating hearth furnace to an elevated temperature of 800 - 850°C, soaking the part completely at the said elevated temperature, placing the part by means of a

mobile charger on turn table, moving downward cover/lid onto the turn table to enclose water-spray ring and the heated part placed on the turn table by means of pneumatic cylinder and starting rotation of the turn table automatically as soon as the cover/lid comes to be in contact with the turn table;
(b) starting the supply of high pressure water from
overhand tank at a pressure of 2.5 - 3.5 kg/cm2 to ring through
two inlets by means of actuator valves automatically as soon as the speed of rotation of the turn table increases to 10 - 15 r.p.m.;
(c) stopping the supply of high-pressure water to the ring
automatically on expiry of a quenching duration of 220 - 260
seconds by actuating a valve provided for the purpose;
(d) flushing out the water left in the water-spray ring
with compressed air from plant by automatically switching on
pressure control valves, raising the cover/lid upward from the
level of the turn table surface automatically by means of
pneumatic cylinders, removing the heat-treated part from the
turn table surface by means of a mobile charger at a temperature
of 500 - 600°C; and
(e) allowing the heat-treated part to self-temper in
natural air by conduction of heat from its core region to its
surface region for a duration of 120 to 180 minutes.
An embodiment of the system used for the invented process is described with reference to the accompanying drawings in which -

Figure 1 is a sketch of the system comprising sources of high pressure water and compressed air supplies, heat-treatment unit, pressure control valves, pneumatic cylinders, actuator operated valves, control cubicle;
Figure 2 shows the sectional diagram of the water-spray ring;
Figure 3 shows the sectional elevation of the heat-treatment unit containing water-spray ring, turn table with the part to be heat-treated placed thereon and driving mechanism for rotating the turn table.
Referring to Fig. 1, water from the water main (M) is stored in the overhead tank (H), typically of capacity 23,000 litre, from which it is supplied through a number of pressure control valves (PCV), two filters (F1, F2), two pumps (P1, P2) for raising the pressure of water to a high level i.e.

5 Kg/Cm , which is supplied to the water-spray ring (R) having a number of nozzles (N) through pressure control valves (PCV) and actuator operated valves (AOV1, AOV2, AOV3). The excess water at high pressure is returned to tank (H) through actuator operated valve (AOV4).
Two infra-red pyrometers (PRM1, PRM2) are provided for measuring the temperature of the heated part placed on turn table (T) enclosed by cover/lid (C). The cover/lid (C) is movable by means of pneumatic cylinder (PNC1) and the part to be heat-treated is placed on the turn table by means of mobile charger and removed from the turn table on completion of the heat treatment by means of mobile charger.
Control cubicle (CC) is supplied with parameters for controlling the operation of the system such as (i) dimensional particulars of the part to be heat-treated, (ii) temperature of the part, (iii) duration of high pressure water supply, (iv) pressure of water supply, (v) flow rate of water supply and (vi) rotational speed of the turn table.
The plant for supplying compressed air (PAS) supplies compressed air to pressure control valves (PCV), pneumatic cylinders (PNC1) and actuator operated valves (AOV1, AOV2, AOV3, AOV4). The used water is collected in sump (SP) and fed back into tank (H).

Referring to Fig. 2, the circular water-spray ring (R) is of internal diameter 1525 mm and made of a tube of internal diameter 38mm. The ring is provided with 16 nozzles (N) at equal intervals along its inner periphery and directed towards its centre. Each nozzle is of length 152 mm/254 mm, having one nipple and two fixing sockets (S), each of internal diameter 18 mm. Two inlets (I) are provided for supplying high pressure water into the ring, each inlet being of internal diameter 38 mm,
Referring to Fig. 3, the table (T) is rotated by means of a driving mechanism comprising motor (M), gearbox (G) and flexible steel coupling (E). The part (P) to be heat-treated is placed on the turn table (T) with the rim of the part (P) being encircled by water-spray ring (R) which is supplied with high pressure water through two inlets (I) through actuator operated valves (AOV1, AOV2). The cover/lid (C) and part (P) are moved by means of pneumatic cylinders (PNC1) which are supplied with compressed air from an air cylinder (A) of internal diameter of 203 mm. Motor (M) and gearbox (G) are disposed with their horizontal axes at the floor level.
Thus the invention provides an improved process for producing annular heat-treated circular sliding and rolling machine parts like wheels of railway wagons and locomotives, using the system as described herein, comprising the following steps in sequence :

(a) heating part (P) in a rotary hearth furnace to a
specified elevated temperature;
(b) soaking the part completely at the said elevated
temperature;
(c) placing the part by means of mobile charger
on turn table (T);
(d) moving downward cover lid (C) onto the turn table to
enclose water-spray ring (R) and the heated part placed on the
turn table by means of mobile charger;
(e) starting rotation of the turn table automatically
as soon as the cover/lid comes to be in contact with the turn
table;
(f) starting the supply of high pressure water from overhand
tank (H) at a specified pressure to water-spray ring (R)
through two inlets (l) by means of actuator valves (AOV1, AOV2,
AOV3) automatically as soon as the speed of rotation of the turn
table increases to a preset limit;
(g) stopping the supply of high-pressure water to the
water-spray ring automatically on expiry of a preset quenching
duration by actuation of a valve provided for the purpose;
(h) flushing out the water left in the water-spray ring with compressed air from plant (PAS) by automatically switching on pressure control valves (PCV);
(i) raising the cover/lid upward from the level of the turn table surface automatically by means of pneumatic cylinders (PNC1);
(j) removing the heat-treated part at a given temperature from the turn table surface by means of mobile charger;

(k) allowing the heat-treated part to self-temper in natural air for a given duration by conduction of heat from its core region to its surface region; characterised in that
(a) the elevated temperature of the part to be heat-
treated is 800-850°C;
(b) high pressure water is supplied to the water-spray
ring at a pressure of 2.5-3.5 kg/cm2;
(c) the supply of water to the water-spray ring is
started as soon as the speed of rotation of the turn table
increases to a limit of 10-15 rpm;
(d) the supply of high pressure water to the water-spray
ring is stopped on expiry of a quenching duration of 220-260
seconds;
(e) the heat-treated part is removed from the turn table
surface for tempering at a temperature of 500-600°C; and
(f) the heat-treated part is allowed to self-temper in
natural air for a duration of 120 to 180 minutes.
A number of locomotive wheels containing carbon 0.57-0.6796 and manganese 0.60-0.85%by weight were heat treated in a steel plant in the invented process under the conditions given in Table I. The aimed at and achieved properties in the heat-treated wheels are given in Table II.
On an average 8 machine parts such as locomotive wheels can be heat-treated per hour in the invented process.

Table I Conditions of Heat-treatment followed for locomotive wheels

(Table Removed)
Table II Properties of Heat-treated locomotive wheels
(Table Removed)
The invented process has a number of advantageous features over the existing process, such as,
(i) variable rate of quenching during the heat treatment; (ii) rotation of the part during heat treatment, leading
to uniform hardness along the rim of the part; (iii) quenching of the part under optimised flow rate and pressure of the quenching water, and optimised orientation and dimensions of the nozzles for spraying the quenching water leading to gradual reduction of hardness from the rim toihe core of the heat-treated machine parts; (iv) suitability for heat-treating machine parts of
versalite dimensions;
(v) minimised consumption of the quenching water; (vi) adjustable conditions for heat-treatment; and (vii) fully automised operations.

We Claim :-
1. An improved process for producing annular heat-treated circular sliding and rolling machine parts like wheels of railway wagons and locomotives, using the system as described herein, characterised in that the process comprises the following steps in sequence :
(a) heating part (P) in a rotating hearth furnace to an
elevated temperature of 800 - 850°C, soaking the part completely
at the said elevated temperature, placing the part by means of a
mobile charger on turn table (T) , moving downward cover/lid (C)
onto the turn table to enclose water-spray ring (R) and the
heated part placed on the turn table by means of pneumatic
cylinder (PNC1) and starting rotation of the turn table
automatically as soon as the cover/lid comes to be in contact
with the turn table;
(b) starting the supply of high pressure water from
overhand tank (H) at a pressure of 2.5 - 3.5 kg/cm2 to ring (R)
through two inlets (I) by means of actuator valves (AOV1, AOV2,
AOV3) automatically as soon as the speed of rotation of the turn
table increases to 10 - 15 r.p.m.;
(c) stopping the supply of high-pressure water to the ring
automatically on expiry of a quenching duration of 220 - 260
seconds by actuating a valve provided for the purpose;
(d) flushing out the water left in the water-spray ring
with compressed air from plant (PAS) by automatically switching
on pressure control valves (PCV), raising the cover/lid upward

from the level of the turn table surface automatically by means of pneumatic cylincers (PNC1), removing the heat-treated part from the turn table surface by means of a mobile charger at a temperature of 500 - 600°C; and
(e) allowing the heat-treated part to self-temper in natural air by conduction of heat from its core region to its surface region for a duration of 120 to 180 minutes.
2. The process as claimed in claim 1, wherein the part
to be heat-treated is heated to an elevated temperature of
810-820°C, water is supplied to the water-spray ring at a
pressure of 3kg/cm2 , the supply of water to the water-spray
ring is started when the speed of rotation of the turn table attains a limit of 15 rpm, the supply of water to the water-spray ring is stopped on expiry of a quenching duration of 240 seconds, the heat-treated part is removed from the turn table surface for tempering at a temperature of 550°C and the heat-treated part is allowed to self-temper in natural air for a duration of 150 seconds.
3. An improved process for producing annular heat-treated
circular sliding and rolling machine parts like wheels of railway
wagons and locomotives, substantially as herein described with
reference to the accompanying drawings.

Documents:

436-del-1998-abstract.pdf

436-del-1998-claims.pdf

436-del-1998-correspondence-others.pdf

436-del-1998-correspondence-po.pdf

436-del-1998-description (complete).pdf

436-del-1998-drawings.pdf

436-del-1998-form-1.pdf

436-del-1998-form-19.pdf

436-del-1998-form-2.pdf

436-del-1998-form-4.pdf

436-del-1998-gpa.pdf

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Patent Number

232210

Indian Patent Application Number

436/DEL/1998

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

16-Mar-2009

Date of Filing

20-Feb-1998

Name of Patentee

STEEL AUTHORITY OF INDIA LIMITED

Applicant Address

ISPAT BHAWAN, LODI ROAD, NEW DELHI-110003.

Inventors:

#	Inventor's Name	Inventor's Address
1	DINESH KUMAR JAIN	RESEARCH AND DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., RANCHI-834002.
2	DAYA SHANKER GOPTA	RESEARCH AND DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., RANCHI-834002.
3	BIMALENDRA ROY	RESEARCH AND DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., RANCHI-834002.
4	SUDHAKAR JHA	RESEARCH AND DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., RANCHI-834002.
5	RAMAKANT SINGH	RESEARCH AND DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., RANCHI-834002.

PCT International Classification Number

C21D 7/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA