FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
AXLE JOURNAL TURNING AND BURNISHING MACHINE
TEH BHOJRAJ HEMRAJ
an Indian National of 18. Vishrambagh Housing Society, Senapati Bapat Road, Pune 411 016, Maharashtra, India
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE INVENTION:
The present invention generally relates to a process and a machine tool used for machining an axle journal of a railway wheel set, more particularly, the present invention relates to a process and a machine tool used for turning and roller-burnishing an axle journal of a railway wheel set.
BACKGROUND OF THE INVENTION:
A wheel set of a railway vehicle includes a pair of wheel discs press fitted on an axle of the wheel set. The wheel set includes a pair of spaced apart out-board axle journals, also called outside journals and a pair of spaced apart in-board axle journals, also called inside journals. The out-board axle journals or outside journals are configured at extreme ends of the axle. The pair of spaced apart in-board axle journals or the inside journals are configured at a portion adjacent to the wheel discs and in between the wheel discs. During the process of running of the railway vehicle the axle journals of the wheel set gets worn out or during the process of press fitting of the wheel discs on the axle, the outboard journals get distorted, thereby requiring overhauling of the wheel set.
During the overhauling of the wheel set, the axle journals are to be machined by turning and roller-burnishing operation for fitment of bearings thereon. The turning and roller-burnishing operation is an extremely precision operation that requires controlling ovality, taper

and surface finish of the journals being machined. For machining the in-board axle journals and the out-board axle journals of the railway wheel set, the wheel set is tightly held between revolving centers of the machine tool thereby causing the wheel set to rotate about an axis of rotation. Thereafter, a tool carriage carrying a turning tool is moved to various portions of the axle that are to be machined. The tool carriage is adjusted to determine a depth of cut and is traversed along an axis that is parallel to the axis of rotation of the wheel set. After completing the turning operation, the turning tool is withdrawn and a pair of diametrically opposite rollers is applied on the turned journals. The rollers are hydraulically pressed against the surface of the turned journals to produce a smooth surface finish.
Further, US Patent Number 4,086,732 issued on May 2, 1978 discloses a grinding apparatus for refinishing the end surface of a railroad locomotive axle without removal of the axle from its operative position in the locomotive which includes a frame having a mounting plate which is adapted to be detachably connected to the journal box that surrounds the axle end surface to be refinished, a shaft supported by said frame and concentrically aligned with the axle, and a powered grinding tool mounted to the shaft and rotatable about the axis thereof, the grinding tool includes a working surface which engages and abrasively refinishes the axle end surface.
However, these conventional processes and machine tools used for carrying out the turning and roller-burnishing operation of the axle

journals does not achieve simultaneous turning or roller-burnishing of spaced apart axle journals in a single pass.
Accordingly, there is a need of a machine tool that is capable of turning or roller-burnishing spaced apart axle journals in a single pass.
OBJECTS OF THE INVENTION:
An object of the present invention is to provide a process and a machine tool capable of simultaneously turning and roller-burnishing spaced apart axle journals in a single pass of a turning and roller-burnishing tool.
Another object of the present invention is to provide a process and a machine tool that is adapted to reduce cycle time for machining a wheel set.
Yet another object of the present invention is to provide a machine tool that is capable of turning as well as roller-burnishing spaced apart axle journals in a single pass, thereby avoiding interruptions and inconvenience of changing the machine tool for changing the operation.
Still another object of the present invention is to provide a machine tool that is capable of turning and roller-burnishing axle journals with the wheel discs of the wheel set in a mounted condition.

Another object of the present invention is to provide a machine tool that is easy to operate and that requires lesser operator interaction for operating the machine tool, thereby reducing fatigue of an operator operating the machine tool.
Yet another object of the present invention is to appreciably reduce floor to floor timing required for turning and roller-burnishing each of the spaced apart out-board axle journals.
One more object of this invention is to provide a process and machine tool that is adapted to facilitate movement of a turning and roller-burnishing tool for performing out-board turning, roller-burnishing operation, in-board turning and burnishing operations.
Yet another object of the present invention is to provide a process and machine tool that is adapted to provide more accuracy for performing out-board turning, in-board turning and roller-burnishing operations.
Yet one more object of the present invention is to provide a machine tool that is adapted to work in non air-conditioned environment with an ambient temperature up to 50°C and relative humidity up to 95%.
Still another object of the present invention is to provide a machine tool that is adapted to perform finishing operation on various fillet radii and shoulder radii of a wheel set in a single pass of a turning and roller burnishing tool.

Further object of the present invention is to provide a machine tool that incorporates safety features to ensure complete protection of an operator from all possible operational failures.
SUMMARY OF THE INVENTION:
A machine tool for simultaneously machining distorted axle journals of a wheel-set to facilitate fitment of wheel-disc supporting bearings on machined axle journals. The machine tool is adapted to machine the axle journals of the wheel-set in a single pass. The machine tool includes a pair of tail stock assemblies, a pair of sliding sleeves, a pair of center assemblies and a pair of tool slide assemblies. Each sliding sleeve of the pair of sliding sleeves is adapted to slide relative to a corresponding tail stock assembly of the pair of tail stock assemblies. Further, each center assembly is functionally coupled to a corresponding sliding sleeve of the pair of sliding sleeves. The pair of center assemblies is adapted to support the wheel set there-between and facilitate rotation of the wheel set about an axis passing through the pair of center assemblies.
Typically, the pair of tail stock assemblies is mounted on a machine bed.
Further, each tail stock assembly includes a hydraulic motor, a lead screw and a box nut to facilitate sliding of the sliding sleeve relative to the tail stock assembly.

Particularly, each tail stock assembly further comprises a plurality of disc springs for facilitating energy dissipation during a burnishing operation and thereby reducing excessive axial load on the center assemblies.
Further, each tail stock assembly includes a gripping mechanism for locking the sliding sleeve inside the tail stock assembly.
Typically, each sliding sleeve includes a tapered bore for accommodating a corresponding center assembly.
Further, the machine tool includes a push button disposed there-on for synchronizing movement of the sliding sleeves relative to corresponding tail stock assemblies.
Typically, each tool slide assembly is adapted to support a radius turning attachment.
Alternatively, each tool slide assembly is adapted to support a burnishing attachment.
Particularly, the burnishing attachment includes a pair of lever arms pivotally connected to each other, each lever arm is provided with a burnishing rollers at a distal end thereof, relative angular movement between the lever arms facilitates application of burnishing pressure on the axle journals of the wheel-set held between the center assemblies.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be explained in relation to the accompanying drawings, in which:
Figure 1 illustrates a front view of a wheel set used for coaches and wagons, depicting areas to be turned and burnished for fitment of the bearings thereon, in accordance with one embodiment of the present invention;
Figure 2 illustrates a front view of a wheel set used for locomotives and motor coaches of electrical multiple units, depicting areas to be turned and burnished for fitment of the bearings thereon, in accordance with one embodiment of the present invention;
Figure 3(a) illustrates a front view of an axle journal turning and burnishing machine, in accordance with one embodiment of the present invention;
Figure 3(b) illustrates a side view of the axle journal turning and burnishing machine, in accordance with one embodiment of the present invention;
Figure 4(a) illustrates a view of the tailstock assembly, in accordance with one embodiment of the present invention;

Figure 4(b) illustrates a sectional view of the tailstock assembly along a section line K-K as illustrated in Figure 4(a), in accordance with one embodiment of the present invention;
Figure 4(c) illustrates another sectional view of the tailstock assembly along a section line D-D as illustrated in Figure 4(b), in accordance with one embodiment of the present invention;
Figure 5 illustrates a sectional view depicting internal details of the revolving center, in accordance with one embodiment of the present invention;
Figure 6 (a) illustrates a view of a radius turning device, in accordance with one embodiment of the present invention;
Figure 6(b) illustrates another view of the radius turning device, in accordance with one embodiment of the present invention;
Figure 6(c) illustrates a sectional view of the radius turning device along a section line K-K as illustrated in Figure 6(b), in accordance with one embodiment of the present invention;
Figure 6(d) illustrates a sectional view of the radius turning device along a section line M-M as illustrated in Figure 6(c), in accordance with one embodiment of the present invention;

Figure 6(e) illustrates another sectional view of the radius turning device along a section line N-N as illustrated in Figure 6(c), in accordance with one embodiment of the present invention;
Figure 7 illustrates a burnishing attachment assembly for the machine tool, in accordance with one embodiment of the present invention;
Figure 8 illustrates a wheel set drive, in accordance with one embodiment of the present invention; and
Figure 9 illustrates a wheel set lifting and centering device, in accordance with one embodiment of the present invention.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.
Referring to Figure 1, the wheel set 100 used for coaches and wagons of the railway vehicle includes out-board axle journal 101(a) and 101(b). The out-board axle journal 101(a) and 101(b) are to be finished by turning and roller-burnishing operation for fitment of bearings thereon. Further, the wheel set 100 also includes collar and shoulder

radii that are to be finished by the turning and roller-burnishing operation.
Referring to Figure 2, the wheel set 200 used for locomotives and motor coaches of electrical multiple units (EMU) includes out-board axle journals 201(a) and 201(b) as well as in-board axle journals 202(a) and 202(b). The wheel set 200 further includes collar and shoulder radii that are to be finished by using a turning and roller-burnishing tool. The axle portion of the wheel set 200 is made of a material having a tensile strength of 70 kg/ mm" or more.
Referring to Figure 3(a) and 3(b), the axle journal turning and burnishing machine tool 1 (hereinafter referred to as "machine tool") used for machining the out-board axle journals 101(a), 101(b), 201(a) and 201(b) as well as in-board axle journals 202(a) and 202(b) of a wheel set 100 or 200 is depicted. The machine tool 1 includes a pair of tailstock assemblies 300(a) and 300(b), a pair of sliding sleeve 305(a) and 305(b), a pair of revolving center assemblies 400(a) and 400(b), a lifting jack assembly 5, a pair of tool slide assemblies 6(a) and 6(b), a bed 7, a motor 8 for tool slide positioning, a centering device assembly 9, a burnishing slide assembly 10, a main drive 11, a motor for turning and burnishing feed 12, an endless belt 13, a control panel 14 and a hydraulic power pack 15.
The machine tool 1 used for machining the out-board axle journals 101(a), 101(b), 201(a) and 201(b) as well as in-board axle journals 202(a) and 202(b) in accordance with the present invention includes a

machine bed 7. The machine bed 7 of the machine tool 1 is having an extremely rigid structure made out of CI casting Gr. FG 260 as per IS 210. The machine bed 7 of the machine tool 1 is accurately machined and hand-scraped to get the required accuracies. The machine bed 7 includes a guide-way system to ensure smooth sliding of a tool carriage over the machine bed 7. The guide way system includes hardened and ground guide-ways incorporated on the machine bed 7. The mating slide ways on the tool carriage are having a lining made of a material having very low co-efficient of friction and very high wear resistance. The guide-ways on the machine bed 7 are adapted to mate with slide ways configured on the tool carriage. The guide-ways system also includes heavy duty way wipers to prevent ingress of swarf into the guide-ways system.
Further, the axle journal turning and burnishing machine tool includes a pair of tailstock assemblies 300(a) and 300(b), each being mounted at opposite ends of the machine tool 1. Each of the pair of tailstock assemblies 300(a) and 300(b) holds a revolving center assembly out of the pair of revolving center assemblies 400(a) and 400(b).
The following description describes the various components of the tailstock assembly 300(a); the tailstock assembly 300(b) is structurally and functionally identical to the tailstock assembly 300(a).
Referring to Figure 4(a) - Figure 4(c), the tailstock assembly 300(a) out of the pair of tailstock assemblies 300(a) and 300(b) includes a tailstock housing 301(a), a hydraulic motor 302(a), a lead screw 303(a), a box

nut 304(a), a sliding sleeve 305(a), a plurality of disc springs 306, a piston rod 307(a), a clamping element 308(a), and an hydraulic cylinder assembly 309(a).
The tailstock assembly 300(a) is mounted onto the machine bed 7 of the machine tool 1. The tailstock assembly 300(a) holds a revolving centre 400(a), which in turn supports an end of an axle journal of a railway wheel set to be machined. The base of the tailstock is accurately machined and scrapped for mounting the tailstock on top of the machine bed 7. The base of the tailstock includes holes for firmly mounting the tailstock on top of the machine bed 7 by means of bolts. The tailstock assembly 300(a) includes tailstock housing 301(a). The tail stock housing centrally houses a hydraulic motor 302(a). The hydraulic motor 302(a) rotates a lead screw 303(a). The lead screw 303(a) engages with a box nut 304(a), which in turn is fixed to a sliding sleeve 305(a). The box nut 304(a) causes the sliding sleeve 305(a) to slide inside a sleeve guiding bore of the tailstock assembly 300(a). The sliding sleeve 305(a) of the tailstock assembly 300(a) includes a tapered bore on a front end thereof to accommodate a suitable revolving centre 400(a) illustrated in FIG. 5. The one side tailstock further includes the plurality of disc springs 306 for facilitating expansion in axle length during the burnishing operations. During the burnishing operation, the axle length tends to increase. The plurality of disc springs 306 get compressed, when the length of the axle gets increased during the burnishing operations. The compression of the plurality of disc springs 306 causes dissipation of energy thereby considerably reducing excessive axial load on the revolving centers 400(a) and 400(b).

Further, the tailstock assembly 300(a) of the machine tool 1 used for carrying out the turning and burnishing operation includes gripping mechanism for tightly gripping the sliding sleeve 305(a) inside the sleeve guiding bore of the tailstock assembly 300(a), thereby inhibiting lateral movement of the sliding sleeve 305(a) inside the sleeve guiding bore of the tailstock assembly. Figure 4(c) illustrates the gripping mechanism for tightly gripping the sliding sleeve 305(a) inside the sleeve guiding bore of the tailstock assembly. The gripping mechanism for tightly gripping the sliding sleeve 305(a) inside the sleeve guiding bore includes a piston rod 307(a) and a clamping element 308(a) that are disposed around the sliding sleeve 305(a). The piston rod 307(a) and the clamping element 308(a) are forced towards a hydraulic cylinder assembly 309(a) upon activation of the hydraulic cylinder assembly 309(a), thereby applying a gripping force onto sliding sleeve 305(a).
During the burnishing operation the gripping force applied by the piston rod 307(a) and the clamping element 308(a) onto the sliding sleeve 305(a) is released, thereby permitting lateral movement of the sliding sleeve 305(a) inside the sleeve guiding bore of the tailstock assembly during the burnishing operation. The lateral movement of the sliding sleeve 305(a) inside the sleeve guiding bore permits lateral movement of the revolving center 400(a), when the axle journal pushes the revolving center 400(a) outwardly due to increase in length of the axle journal due to axial loads acting on the axle journal during simultaneous burnishing of both the axle journals.

The movement of both the sliding sleeves 305(a) and 305(b) corresponding to tailstock assembly 300(a) and 300(b) is synchronized through a single push button control provided at a suitable location on a side of the machine tool 1, where driving controls are provided.
The machine tool 1 includes a pair of revolving centers 400(a) and 400(b) to support the axle journal to be machined there between. Figure 5 illustrates a sectional view depicting internal details of a revolving center 400(a) out of the pair of revolving centers 400(a) and 400(b). The revolving centre 400(b) is structurally identical to the revolving centers 400(a).
Referring to Figure 5, the revolving centre 400(a) includes a center bullet 401(a), a center housing 402(a), a ball thrust bearing 403(a), a taper bore cylindrical roller bearing 404(a), a spacer 405(a), a lock nut 406(a), and a plurality of precision angular contact bearings 407(a). In one embodiment of the present invention, the center bullet 401(a) may be composed of an En31 alloy steel as per BS 970. Further, the center bullet 401(a) may be hardened and grounded. The center bullet 401(a) is housed inside a center housing 402(a). The center housing is made of case hardened steel En36/EN353/EN354 as per BS 970. The revolving centre utilizes a very rigid and accurate bearing assembly for supporting the center bullet 401(a) inside the center housing 402(a). The revolving centre 400(a) is able to withstand very high axle thrust and wheel set weight because of arrangement of the bearing assembly.

The bearing assembly for supporting the center bullet 401(a) inside the center housing 402(a) includes a ball thrust bearing 403(a). The ball thrust bearing 403(a) of the revolving center bearing assembly permits the revolving center 400(a) to bear heavy axial loads applied thereto by the journal axle due to increase in the axle length due to axial load acting on the journal axle because of the simultaneous burnishing of both the out-board axle journals. The bearing assembly for supporting the center bullet 401(a) inside the center housing 402(a) further includes a taper bore cylindrical roller bearing 404(a). The internal clearance between the cylindrical roller bearing 404(a) may be manipulated by adjusting a spacer 405(a) disposed there between. After adjusting the clearance, the taper bore cylindrical roller bearing 404(a) may be locked by adjusting a special lock nut 406(a). The taper bore cylindrical roller bearing 404(a) of the bearing assembly is capable of taking up radial loads of the wheel set supported between the revolving centers 400(a) and 400(b). Further, the plurality of precision angular contact bearings 407(a) may be incorporated on the rear end to provide controlled accuracy and to permit pre-loading of the thrust bearing 403(a).
The machine tool 1 also includes the pair of tool slide assemblies 6(a) and 6(b) (shown in Figure 3(a)) incorporated on each side thereof to facilitate positioning of the axle turning tool or the burnishing roller for carrying out the turning and burnishing operations. The tool slide assembly 6(a) includes a main longitudinal slide assembly, an auxiliary longitudinal slide assembly, and a cross slide assembly.

The main longitudinal slide may have a ribbed structure made of closed grained C.I casting Grade FG 260 to IS: 210. The main longitudinal slide may be thermally stress relieved and aged to retain dimensional stability. One of the main longitudinal slide utilizes a lead screw and a nut mechanism to move on guide ways provided on the machine bed 7. One of the longitudinal slide is fixed to the machine bed 7. The main longitudinal slide is accurately machined and hand scrapped to provide an accurate surface for sliding on guide ways provided on the machine bed 7. The main longitudinal slide may also include a separate drive motor to drive the lead screw. Further, the main longitudinal slide may also include a wear adjustment gib to take up wear during use. Furthermore, the main longitudinal slide also includes way wipers provided at the guide ways for preventing ingress of dust, dirt, chips etc. The main longitudinal slide includes hydraulic clamps provided on either side of the tool slide to clamp the slide with the machine bed 7 upon completion of the longitudinal movement of the tool slide.
The auxiliary longitudinal slide is adapted to provide a longitudinal motion to the tool or the burnishing roller while performing axle turning and burnishing operation. The auxiliary longitudinal slide is made from Grade 600/3 S.G. iron castings as per IS: 1865.The auxiliary longitudinal slide is properly stress relieved and aged to retain dimensional stability. The auxiliary longitudinal slide is adequately ribbed to withstand the cutting forces developed during the turning and burnishing operation. The auxiliary longitudinal slide includes slide-ways that may be provided with SKC linings to give long trouble-free service. Further, the auxiliary longitudinal slide may also include a

wear adjustment gib to take up wear during use. Furthermore, the auxiliary longitudinal slide also includes way wipers provided at the guide ways for preventing ingress of dust, dirt, chips etc. The auxiliary longitudinal slide also includes a safety clutch to prevent accidental overloading of the slide. The auxiliary longitudinal slide utilizes a lead screw and a nut mechanism to achieve feed motion of the auxiliary longitudinal slide.
The tool slide assembly 6(a) further includes a cross slide that is mounted on a top surface of the auxiliary longitudinal slide. The cross slide is adapted to slide in the dovetail guide-ways provided on the top of auxiliary longitudinal slide. Further, the cross slide is adapted to carry a turning attachment at one end and a burnishing attachment at another end. The cross slide may be made from S.G. Iron Grade 600/3 material as per IS: 1864. The cross slide may be amply ribbed to sustain the cutting as well as burnishing forces. Further, the cross slide may also include a wear adjustment gib to take up wear during use. Furthermore, the cross slide also includes way wipers provided at the guide ways for preventing ingress of dust, dirt, chips etc. The cross slide utilizes a lead screw and a nut mechanism to achieve cross motion of the cross slide.
Referring to Figure 6(a) - Figure 6(e), a radius turning attachment is mounted on one side of the tool slide assembly. The radius turning attachment includes a clamping lever 450, a tool slide 452, a compound slide 454, a needle roller bearing 456, an eccentric shaft 458, a helical

gear 460, a swing tool holder 462, a bracket for swing tool 464, a limit switch 466, and a gear 468.
The axle turning tool may be mounted on the swing tool holder 462. The axle turning tool is having a lever to swivel the tool holder 462. The tool holder 462 may also be connected to hand wheel through suitable gearing such as the helical gear 460, the gear 468 and the eccentric bushes controlling the radius. The motion from the hand wheel is transferred to the tool. The tool holder 462 includes the limit switch 466 for sensing at 90 degree of travel so that as soon as the radius turning is over, linear motion can be started without any interruption. The radius turning arrangement is capable of uninterrupted cutting at transition between fillets and the cylindrical portion of the journal motor bearing seat without any break or chatter marks. The radius turning attachment is adapted to turn the radii at various locations on the axle journal. These radii are critical and are to be merged with the straight portion of the axle without any interruption.
Referring to Figure 7, the burnishing attachment assembly includes a top lever 501(a) and a bottom lever 501(b). Each of the top lever 501(a) and the bottom lever 501(b) include a burnishing roller secured to a front end thereof. Further, each of the top lever 501(a) and the bottom lever 501(b) is independently hinged on hinge pins 502(a) and 502(b) respectively. The top lever 501(a) and the bottom lever 501(b) are interconnected by small levers 503(a) and 504(a) to ensure equal amount of movement of the burnishing roller mounted levers 501(a) and 501(b). Further, the top lever 501(a) includes a hydraulic cylinder

505 mounted thereon. The piston rod of the hydraulic cylinder 505 is coupled to the bottom lever via a bearing bolt 506. Both the burnishing roller mounted levers 501(a) and 501(b) may travel towards the machine center, when the hydraulic cylinder 505 is pressurized in one direction, thereby applying burnishing pressure on the axle journal supported between the revolving centers 400(a) and 400(b).
Referring to Figure 8, the machine tool 1 further includes a wheel set drive assembly 600. The wheel set drive assembly may be used for rotating the wheel set after mounting the wheel set between the revolving centers 400(a) and 400(b). The wheel set drive assembly includes a suitable drive system for transmitting drive to the wheel set supported between the revolving centers 400(a) and 400(b).
The wheel set drive 600 includes a driving belt 601, a pulley 602, a hydraulic cylinder 603, a base plate 604, a motor 605, a belt tensioning device 606, a gear box 607, and a top slide 608. The wheel set drive 600 may be used for rotating the wheel set after mounting between centers. The motor 605 may be coupled to the reduction gear box 607 with speed changing facility. The pulley 602 may be mounted on an output shaft of the gear box 607. The pulley 602 may be coupled to the wheel set by endless belt 601. A provision may be incorporated in such a way that one single endless belt may take care of various wheel diameters falling within the range as specified in leading parameters. Hydraulic belt tensioning arrangement may be incorporated to give constant tension on the belt. The wheel set drive 600 may be mounted

on an end portion of the machine tool 1 that is opposite to an operator side.
The machine tool 1 further includes a drive system that includes a belt drive with an automatic belt tensioning device. The drive system is designed in such a way that drive system does not interfere with the turning and burnishing operation, when turning or burnishing is simultaneously carried out at each axle journal of the pair of work-hardened out-board axle journals.
Referring to Figure 9, the machine tool 1 further includes a wheel set lifting and centering device 700. The wheel set lifting and centering device 700 includes a centering device assembly 9 and a wheel set lifting jack assembly 5. The centering device assembly 9 includes a lever 701, a guide bar 702, a limit switch 703, a swing arm 704.
The machine tool 1 further includes the lifting jack assembly 5 for lifting, centering and lowering the wheel sets. The movement of lifting jack assembly 5 may be automatically controlled to bring the wheel sets in the centering position just a little bit below the centre line of the live revolving centers 400(a) and 400(b). The lifting jack assembly 5 works with the centering device assembly 9 to provide complete synchronization.

TECHNICAL ADVANTAGES AND ECONOMIC
SIGNIFICANCE:
The machine tool of the present invention is capable of simultaneously turning or burnishing spaced apart axle journals in a single pass of a turning and roller-burnishing tool. Further, the machine tool is adapted to reduce cycle time for machining a wheel set. Furthermore, the machine tool is capable of turning as well as roller-burnishing spaced apart axle journals in a single pass, thereby avoiding interruptions and inconvenience of changing the machine tool for changing the operation. Moreover, the machine tool is capable of turning and roller-burnishing axle journals with the wheel discs of the wheel set in a mounted condition. Additionally, the machine tool is easy to operate and requires lesser operator interaction for operating the machine tool, thereby reducing fatigue of the operator operating the machine tool. Also, the machine tool is adapted to reduce floor to floor timing required for turning and roller-burnishing each of the spaced apart out-board axle journals.
Further, the machine tool is adapted to facilitate movement of a turning and roller-burnishing tool for performing out-board turning, roller-burnishing operation, in-board turning and burnishing operations. Furthermore, the machine tool is adapted to work in non air-conditioned environment with an ambient temperature up to 50°C and relative humidity up to 95%. Moreover, the machine tool is adapted to perform finishing operation on various fillet radii and shoulder radii of a wheel set in a single pass of a turning and roller burnishing tool. Additionally,

the machine tool adapted to incorporate safety features to ensure complete protection of an operator from all possible operational failures. Moreover, the machine is adapted to be of robust, rigid and of sturdy construction that is capable of working under severe railway workshop conditions and is free from all undue vibrations.
While considerable emphasis has been placed herein on the particular features of this invention, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other modifications in the nature of the invention or the preferred embodiments 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 invention and not as a limitation.

I Claim:
1. A machine tool for simultaneously machining axle journals of a wheel-set in a single pass, thereby facilitating fitment of wheel-disc supporting bearings on machined axle journals, said machine tool comprising:
• a pair of tail stock assemblies;
• a pair of sliding sleeves, wherein each sliding sleeve is adapted to slide relative to a corresponding tail stock assembly of said pair of tail stock assemblies;
• a pair of center assemblies, wherein each center assembly is functionally coupled to a corresponding sliding sleeve of said pair of sliding sleeves; said pair of center assemblies adapted to support said wheel set there-between and facilitate rotation of said wheel set about an axis passing through said pair of center assemblies; and
• a pair of tool slide assemblies, wherein each tool slide assembly is adapted to facilitate relative motion between a tool carriage holding a machining tool and said wheel-set supported between said pair of center assemblies, said tool carriage is adapted to hold a turning tool or a burnishing tool for carrying a turning or burnishing operation on said axle journals.

2. The machine tool as claimed in claim 1, wherein said pair of tail stock assemblies is mounted on a machine bed.
3. The machine tool as claimed in claim 1, wherein each tail stock assembly comprises a hydraulic motor, a lead screw and a box nut

to facilitate sliding of said sliding sleeve relative to said tail stock assembly.
4. The machine tool as claimed in claim 1, wherein each tail stock assembly further comprises a plurality of disc springs for facilitating energy dissipation during a burnishing operation and thereby reducing excessive axial load on said center assemblies.
5. The machine tool as claimed in claim 1, wherein each tail stock assembly further comprises a gripping mechanism for locking said sliding sleeve inside said tail stock assembly.
6. The machine tool as claimed in claim 1, wherein each sliding sleeve comprises a tapered bore for accommodating a corresponding center assembly.
7. The machine tool as claimed in claim 1, further comprises a push button disposed thereon for synchronizing movement of said sliding sleeves relative to corresponding tail stock assemblies.
8. The machine tool as claimed in claim 1, wherein each tool slide assembly is adapted to support a radius turning attachment.
9. The machine tool as claimed in claim 1, wherein each tool slide assembly is adapted to support a burnishing attachment.
10. The machine tool as claimed in claim 1, wherein said burnishing attachment comprises a pair of lever arms pivotally connected to each other, each lever arm is provided with a burnishing rollers at a distal end thereof, angular movement between said lever arms relative to each other facilitates application of burnishing pressure on said axle journals of said wheel-set held between said center assemblies.