FORM 2
THE PATENT ACT 1970 (39 of 1970)
&
The Patents Rules, 2003 COMPLETE SPECIFICATION
(See Section 10, and rule 13)
1. TITLE OF INVENTION
6 AXES HIGH SPEED CNC GEAR HOBBING MACHINE PHC 2 50
2. APPLICANT(S)
a) Name :- PREMIER LIMITED
b) Nationality : INDIAN Company
c) Address : 58, NARIMAN BHAVAN,
NARIMAN POINT, MUMBAI-400 021, MAHARASHTRA, INDIA
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -

FIELD OF INVENTION
The present invention in general relates to a process of high speed CNC Gear hobbing and more particularly to a gear hobbing machine.
BACKGROUND OF THE INVENTION
Hobbing is a machining process for making of gears, sprockets etc. by a cutting tool called hob. It is a comparatively inexpensive process but suffers from a problem that the speed variations between the rotating workpiece and the hob can not be synchronized to the micro-level details. Also, a lot of time is required to mechanically change various settings of the machine, which increases the chances of human error. Thus such process is slow and lacks detailed precision while making gears by such hobbing process.
In the hobbing process workpiece and hob rotate together like pair of gears with crossed axes. Gear hobbing is a continuous generating process in which tooth flanks on the constantly rotating workpiece are formed by the equally spaced cutting edges of the hob. The table rotation and hob rotation are synchronized for gear generation. To synchronize the hob axis with the workpiece axis, is a challenge faced in such technological field from time immemorial.
Hobbing machine is equipped with automatic work cycles for Radial, Axial and Tangential hobbing and also in such combinations as Radial - Axial, Radial -Tangential, for setting every movement, machine can be actuated either in rapid traverse by push buttons or manually. Such manual operation may result in misalignment of the hob and workpiece resulting in faulty gear generation.
Further axial, radial and tangential hobbing is possible on hobbing machine during Climb hobbing or Conventional hobbing.

The different types of nobbing methods present in the art are detailed as follows:

Method Manner of operation Application
Axial method Hobbing with axial feed Spur gears with hob by
Climb Hobbing cutting direction and relative hobbing method and with
feed direction of workpiece side milling cutter by index
are same. method.
Axial method Hobbing with axial feed. Worms with hob by hobbing
Conventional hobbing Cutting direction and relative feed direction of workpiece method.
are opposite Worms with side milling cutter by index method.
Radial method Hobbing with radial feed Worm wheels with hob or fly cutter by hobbing method. Hourglass worms with Fellows type cutter by reverse hobbing method.
Radial-Axial Method Plunge to cutting depth with radial feed, immediately followed by hobbing with axial feed by climb or See Axial method above.
conventional hobbing.
The gear blanks are required to be produced with consideration of grade of accuracy of the gear, to be hobbed. Gear blank is the semi-finished part used for the manufacture of a gear by hobbing operation.
The blank needs to gashed all around to produce the required number of teeth & profile of gear. The gashes or the slitting saw allow the hob to cut and pull the blank around and the cuts correct no. of teeth.

The gear blank needs to be located & clamped at the specified height of hobbing machine and the whole blank needs to be stiff enough to resist cutting & clamping forces during the cutting process. Gear teeth needs to be exactly concentric and parallel to the table spindle axis. Such precision are almost impossible to achieve in manually set gear hobbing machines. Thus there existed a long felt need in the art to develop a gear hobbing machine which can provide more precision and accurate gear tooth profile & finish of the gears as per the design of gear and also reduce the setting time, substantially.
All through out the specification including the claims, the words "Hobbing", "Gear", "Machine bed", "Motor", "Servomotor", "Control panel", "Work piece", "Table slide", and "Hob", "Hob head", "Hob head slide" and "electronic gear box" are to be interpreted in the broadest sense of the respective terms and includes all similar items in the field known by other terms, as may be clear to persons skilled in the art. Restriction/Limitation if any, referred to in the specification, is solely by way of example and understanding the present invention.
OBJECTS OF THE INVENTION
It is the principal object of the present invention to provide a High Speed CNC Gear Hobbing Machine to achieve unprecedented reduction of manufacturing costs.
It is further object of the present invention to shorten machining times with efficient utilization of the latest technology in cutting tools.
It is further shortened by virtually eliminating safety margins for slide travels at the beginning & end of hobbing cycle.
It is yet another object of the present invention to provide remarkable change in feed & cutting speed during hob approach & hob exit.

It is a further object of the present invention to provide a 6 Axes High speed CNC Gear Hobbing Machine equipped a unique type of quick hob change system, which saves more than 90% of changing time assuring hob Conce ntricity.
It is a further object of the present invention to provide a gear hobbing machine achieving optimized hob life with utilization of entire usable hob length.
It is further object of the present invention to provide a gear hobbing machine with direct drive for Rotary Table & Spindle which reduces component setting time and elimination of backlash in kinematics. The Direct drive for Rotary Table eliminates indexing & reversing change gears for manufacture of variety of gears.
SUMMARY OF THE INVENTION
The present invention discloses a 6 Axes High speed CNC Gear Hobbing Machine comprising, Machine Bed, a Table drive for mounting a workpiece for rotation about a defined axis, a Main Column traveling on said Machine Bed, a Tail Stock Column mounted on Machine Bed, a Hob Head associated to a Hob Head Slide, and an Electrical panel equipped with an electronic calculating means for monitoring the entire said hobbing process.
In accordance to some preferred embodiment of the 6 Axes High Speed CNC Gear Hobbing Machine oi the present invention:
- Said Table drive is integral part of Rotary Table and is mounted in the said Machine bed;
- Tail stock column mounted on Main Bed.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The nature and scope of the present invention will be better understood from the accompanying drawings, which are by way of illustration of some preferred embodiments and not by way of any sort of limitation. In the accompanying drawings,
Fig 1 illustrates perspective General layout of the present invention.
(Fig. la - Elevation view of the General layout of machine & Fig. lb - Plan view of General layout of the machine.
Fig 2 illustrates the linear X-axis layout of Main Column radial movement.
Fig 3 illustrates the linear Y-axis of 6 axes High Speed CNC Gear Hobbing Machine and movement of Tangential slide (37).
Fig 4 illustrates the linear Z-axis layout of 6 Axes High Speed CNC Gear Hobbing Machine for vertical (Axial) movement of Hob head slide.
Fig 5 schematically illustrates the X-axis kinematics with ball screw, X axis servo motor & Timer pulley & belt.
Fig. 6 schematically illustrates the Y axis kinematics with ball screw, Y axis servo motor & coupling.
Fig. 7 illustrates Z axis kinematics with ball screw, Z axis servo motor & coupling.
Fig. 8 illustrates A axis kinematics for Hob Head Swivel with ball screw, servo motor & coupling.

Fig. 9 illustrates B axis kinematics for hob rotation with spindle motor & hob arbor.
Fig. 10 illustrates C axis kinematics For Table rotation with Stator / Rotor drive.
DETAILED DESCRIPTION OF THE INVENTION
The following describes some preferred embodiments of the present invention, which are purely for the sake of understanding the present invention and not by way of any sort of limitation.
The present invention in general relates to production of gears and in particular to a gear nobbing machine and a methodology for high productivity & versatility high speed hobbing of gears. The present invention aims to counteract the drawbacks of manual setting of various parameters of the machining process according to the varied gears. In the present invention aimed for unprecedented reduction of manufacturing cost with the provision of:
(i) Reduced unproductive time by efficient utilization of latest technology
in cutting tools. (ii) Quick Hob change system achieving saving of more than 90% of hob
change time assuring reliable hob concentricity. (iii) Utilization of entire usable hob length to increase the hob life to a
considerable extent. (iv) To minimize idle times.
The present invention related generally to High Speed CNC Gear Hobbing Machine and more specifically to a new and unique 6 Axes High Speed CNC Gear Hobbing Machine with direct motorized Table drive with synchronous motor for higher torque . It is equipped with stator & rotor to achieve desired integration

The 6 Axes High Speed CNC Gear Hobbing Machine with as disclosed in the present
invention illustrated in Figure-1 primarily comprises of:
1. Bed
2. Main Column
3. Hob Head
4. Tail Stock (Support) Column
5. X axis linear motion motor with encoder.
6. Y axis linear motion motor with encoder.

7. Z axis linear motion motor with encoder
8. A axis rotary motion motor with encoder
9. B Axis rotary motor for Hob rotation.
10. C axis rotary Table Drive
11. Ball screw X Axis
12. Ball screw Y Axis
13. Ball Screw Z Axis
14. Control Panel
15. Operator Pendant
16. Transformer (Not shown as optional)
17. Spindle & Table Motor Cooling Unit
18. Hyd. Power Pack
19. Hyd. Cylinder (Tailstock Slide)
20. Rotary Table
21. M/c Cladding
22. Chip Conveyor
23. Levelling Wedges
24. Cutter - Hob
Machine Bed (1): The Machine bed (1) supports the Main Column (2) and the Rotary table (20) on which workpieces are mounted.

Table Drive (10): The Rotary Table (20) is driven by a direct synchronous motor for higher torque to realize high performance motion control. This is equipped with stator & rotor for easy adaptation to achieve desired integration and high accuracy.
The Main Column (2) is moved radially in and out (X-axis) by AC servo motor (5) and Preloaded ball screw (11) for accurate depth.
Hob head with Hob Head slide (3): Y Axis motion of Tangential Slide (37) is effected through Y axis Ball Screw (12) & Servo motor (6).
Hob Head Slide (3) is moved up and down (Z-axis) by AC servomotor (7) & Ball Screw (13).
Figure-1 illustrates a perspective layout of the 6 Axes High Speed CNC Gear Hobbing Machine and all its different components. The Spindle motor (9) is closely associated with the Hob head (3) providing drive to the hob acting as the cutting tool. The figure illustrates the position of the Control panel (14). The operative association of the Hob head with the Hob slide (3) shown in figure 4 along which the hob moves is also shown in the figure. The figure also illustrates the Main Column (2) and the Tailstock Column (Supporting column) (4) in which the latter houses the support slide along which the work piece translated to associate with the hob. The Machine cladding (21) and the position of the Bed bottom (IB) are also specified in the said figure 1).
The 6 Axes High Speed CNC Gear Hobbing Machine in the present invention comprises a Main Column (2) with Hob head with Hob slide (3) located on Machine Bed (1) which is mounted on floor by using Leveling wedges (23) . Hob head (3) is mounted on Main Column (2) and slides up and down. Hob head slide (shown in figure 4) mounted on Hob head (3) has tangential travel.

The said machine consists of a work piece mounted on Rotary Table (20). The work piece receives motion from motorized table drive. Hob is mounted on Hob head Slide which gets the motion from Spindle motor (9).
For swiveling of Hob Head (3), Worm and Worm wheel Assembly (43) mechanism is provided. Servo drive (A Axis) is used for accurate swiveling of Hob Head for cutting helical gears.
The Machine Bed (1) supports the Main Column (2) the Rotary Table (20) and Tailstock Column (Support Column) (4) Universal Hob head (3) is mounted on Main Column (2) for vertical movement by a Ball screw (13) & Servo motor (7). A hob is mounted on a Hob head slide which has tangential travel and rotate by a Spindle motor (9). The Machine Bed (1) is in box shape.
A work piece mounted on the table rotates through Table index drive. A workpiece and Hob rotate together like a pair of gear with crossed axes. The hob receives motion from the Spindle motor (9) and workpiece receives motion from Table drive. Workpiece mounted between Tailstock center and Table, said machine comprising 6 axes are
i. Horizontal Axis (Radial movement of Column) - X Axis
ii. Vertical Axis (Vertical movement of Hob Head)- Z Axis
iii. Cross Axis (Tangential movement of Hob slide) - Y Axis
iv. Swivelling Axis (Hob head swivel) - A Axis
v. Hob rotation - B Axis
vi. Rotary movement (Table rotation with workpiece) - C Axis
The workpiece axis is perpendicular to the Table axis. The Hob comprising it's axis cross to workpiece and Table axis.

The Main Column (2) located on said Bed (1) being moveable in radial direction along X Axis. The Rotary Table includes a means for mounting a workpiece for rotation about an axis of rotation of said workpiece. A Hob head slide located on said Main Column (2) being moveable along Z axis in a direction perpendicular to both Y and X Axis.
A hob spindle housing comprises a means for mounting Hob spindle. The later further comprises a means for mounting hob for rotation about an axis of rotation of said hob means for controlling the movement of hob slide in a direction along an axis Y means for controlling the movement of said hob in tangential direction.
The hob as disclosed in the present invention is a cutting tool having serrations along the cutter tooth flank which form series of cutting edges that remove the metal. The Hob head can be swiveled at an angle between + / - 45 degree with respect to Hob head slide axis mounted on Main Column.
The machine also comprises a in built Coolant Tank and Chip Conveyor (22) for the removal of chips.
Fig 2 and Fig 3 as illustrated, provides the linear X axis and liner Y axis layout of the disclosed High Speed CNC Gear Hobbing machine with AC servomotor is defined for radial as well as tangential movements of the hob. In the said figures it would be further observed that the AC servomotor is associated with an encoder which converts the electronic signals and controls the electrical output to the motor.
The machine as disclosed in the present invention possesses three axes. The work piece is mounted on Table which is driven by direct Table drive. Rotary hob operates at max. Speed of 3000 rpm. The hob removes metal to cut out the shape of the gear. The relationship of axis of Hob and the axis of work piece is crossed.

In this machine vertical axis of Hob head movement is designated as 'Z' axis. Radial movement of the Table slide on Bed is designated as 'X' axis. Tangential movement of Hob slide is designated as 'Y' axis. The swivel axis of Hob head is designated as 'A' axis and rotary movement of work piece is designated as 'C axis.
With the use of direct Table drive complete chain of reversing and indexing change gears are eliminated and it is possible to cut any no. of teeth (within the machine capacity). Setting time is drastically reduced.
Fig 4 and Fig 5 similarly illustrates the Z axis and X-axis view of the High Speed CNC Gear Hobbing Machine. Similar numbering has been provided to identical components in said figure, as in earlier figures, only for the sake of easier understanding. In the said figures the position of the Ball screw (13 & 11) is shown for the said machine. Figure 5 further illustrates the positions of the Pulley (31), the AC servo motor (5), the Column (2) and the Machine Bed (1)
Fig. 6 schematically illustrates the drive system of Y axis motion according to the present invention. Similar numbering has been provided to identical components in said figure, as in earlier figures, only for the sake of easier understanding. The said figure illustrates the position of the Ball screw (12) and the Servo motor (6)
Fig. 7 illustrates the drive system of Z axis motion Ball screw (13), Servo motor (7) & Coupling (41).
Fig. 8 illustrates - 'A' axis kinematic for Hob Head swivel showing Warm & Warm Wheel Assembly (43).
Fig. 9 illustrates 'B" Axis rotation of Hob with Spindle motor (9) Hob Arbor (25) Hob (24).
Fig. 10 illustrates 'C Axis rotation of Rotary Table (20) with stator / rotor drive.

The following are the few non limiting advantages of the present invention:
1. Dwelling
2. Auto Hob shift
3. Crown Hobbing
5 Taper Hobbing
6. Axial Hobbing
7. Radial Hobbing
8. Radial axial Hobbing
9. Tangential Hobbing
10. Multi cut Cycle
11. Skip Feed
The present invention has been described with reference to some drawings and preferred embodiments, purely for the sake of understanding and not by way of any limitation and the present invention includes all legitimate developments within the slope of what has been described herein before and claimed in the appended claims.

WE CLAIM:
1. A 6 Axes High Speed CNC Gear Hobbing Machine comprising, at least one Machine Bed, a Table drive for mounting a workpiece for rotation about a defined axis, a Main Column movable type on said Machine Bed, a Tail Stock Column mounted on said Machine Bed and being located on a Table, a Hob Head associated to a Hob head slide, and an Electrical panel,
2. The 6 Axes High Speed CNC Gear Hobbing Machine as claimed in claim 1 wherein said Table drive is integral with the concerned Table and is mounted on said Machine Bed.
3. The 6 Axes High Speed CNC Gear Hobbing Machine as claimed in claim 1 wherein said Table drive is mounted on Machine Bed.
4. A 6 Axes High Speed CNC Gear Hobbing Machine substantially as herein described particularly with reference to the accompanying drawings.
5. A method for hobbing of gear substantially as herein described particularly with reference to the accompanying drawings.