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
A GEAR HOBBING MACHINE
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 gear hobbing machine and more particularly to a gear hobbing machine equipped with an electronic processor for accurately calculating and providing suitable commands for movement of different components of the machine.
BACKGROUND OF THE INVENTION
Hobbing is a machining process for making of gears, sprockets etc. by a cutting tool called a 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 nobbing is possible on hobbing machine during Climb hobbing or Conventional hobbing.
The different types of hobbing methods present in the art are detailed as follows:

Method Manner of operation Application
Axial method Climb Hobbing Hobbing with axial feed cutting direction and relative feed direction of workpiece are same. Spur gears with hob by hobbing method and with side milling cutter by index method.
Axial method Conventional hobbing Hobbing with axial feed. Cutting direction and relative feed direction of workpiece are opposite Worms with hob by hobbing method.
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 conventional hobbing. See Axial method above.
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 be gashed all around to produce the required number of teeth and 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 and clamped at the specified height of hobbing machine and the whole blank needs to be stiff enough to resist cutting and 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 and 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", "axial 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 gear hobbing machine which is adopted to machine a gear with less change over time and to accurate and precise shape by a hob.
It is a further object of the present invention to provide a gear hobbing machine adopted to generate a gear to a predefined design which does away with the use of a manual alignment and setting of hob along different axes for hobbing different gears.
It is yet another object of the present invention to provide a gear hobbing machine wherein the drawbacks of manually aligning the hob to different angles accurately and precisely according to the rotation of the work piece, is overcome.
It is a further object of the present invention to provide a gear hobbing machine which is adopted to generate a gear to a predefined design which can automatically

align the Hob in varied angles along different axes as required for machining varied gears.
It is yet another object of the present invention to provide a gear hobbing machine which is adapted to generate a gear to a predefined design which possess an electrical control equipped with electronic calculating means for precisely controlling the speed of the hob according to the speed of rotation of the workpiece in case of variations.
How the foregoing objects are achieved and the other aspects of the present invention will be clear from the following description, which is purely by way of understanding and not by way of any sort of limitation.
SUMMARY OF THE INVENTION
The present invention discloses a gear hobbing machine comprising, at least one machine bed, a table drive on said machine bed for mounting a workpiece for rotation about a defined axis, a Main column (2) moving on said Machine Bed (1), a Tail Stock Column (5) mounted on said machine bed and Table Housing (31), a Hob head (4) associated to a hob head slide, a Control Panel (Electrical panel) equipped with an electronic calculating means for monitoring the entire hobbing process (13) and an electronic gear box.
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 la illustrates the perspective layout of the gear hobbing machine as disclosed in the present invention.
Fig lb illustrates the plan view of the gear hobbing machine as disclosed in the present invention.
Fig 2 illustrates the A-axis layout of the gear hobbing machine as disclosed in the present invention.
Fig 3 illustrates the B-axis layout of the gear hobbing machine as disclosed in the present invention.
Fig 4 illustrates the C-axis Layout of the gear hobbing machine as disclosed in the present invention.
Fig 5 illustrates X Axis layout of ball screw and motor
Fig. 6 illustrates X axis layout of the AC Servo Motor
Fig. 7 illustrates Y Axis layout of the AC Servo Motor
Fig. 8 illustrates Z Axis layout of the AC Servo Motor
Fig. 9 illustrates Z Axis layout of Ball Screw and Motor
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 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 and also the controlling of speed of the hob in accordance with the speed of rotation of the workpiece. This is important for more precise and accurate generation of gears which overcomes the problems faced by varied speeds of the workpiece which resulted in improper machining. In the present invention the various setting parameters can be automatically adjusted to suit a variety of gears as and when the gears needed to be produced.
The present invention relates generally to Gear Mobbing Machine and more specifically to a new and unique Gear Hobbing Machine with electronic gear box, which is adopted to regulate the speed of the Hob and workpiece to accurately machine varied gears precisely according to predetermined designs.
The Gear Hobbing machine with Electronic Gear Box (EGB) as disclosed in the present invention illustrated in Figure-1 primarily comprises of:
1 Machine Bed
2 Main Column
3 Axial slide for Up-Down adjustment (Z axis) of Hob Head
4 Hob Head
5 Tail Stock column (Support Column)
6 Rotary Table
7 Machine Bed Bottom

8. X Axis Drive
9. Z Axis Drive
10. C Axis Drive
11. Y Axis Drive
12. B Axis Drive

13. Control Panel with Electronic Gear Box (EGB)
14. Magnetic Chip Conveyor
15. Machine Enclosure
16. In built Coolant Tank in Bed
17. Hyd. Power Pack
18. Job loading manually
19. Levelling wedges
54. A Axis drive
Machine Bed (1): The Machine Bed (1) supports the Main Column (2) and the Rotary table (6) on which workpieces are mounted.
Fig lb illustrates the plan view of the gear hobbing machine as disclosed in the present invention. Similar numerals have been used to refer to similar features in the invention for the sake of easy understanding.
Fig 2 illustrates the A-axis Linear layout with the position of the Worm shaft (52), Worm Wheel (53), AC Servo motor (49), Gear Box (50), Coupling (51) and Axial Slide (3)
Fig 3 illustrates the B-axis layout with the position of the Hob Head (4), Hob Spindle (26), Tangential Slide (27), Brake Gear (24), Pulley (21 and 22) and Motor (20). Figure 3 further details the position of the Gear (23,25).
The Table drive indexing is integrated in the Table housing (31) as shown in figure 4. The table rotation and hob rotation are synchronized for gear generation through Electronic gear box (EGB). Accuracy of hobbing depends upon the accuracy of index worm drive. A high contact ratio of gears ensures a high load carrying capacity and conservation of accuracy.

Main Column (2) is moved radially in and out (X-axis) by AC Servo Motor (36) and preloaded Ball Screw (39) as shown in figure 5 for accurate depth.
Fig 4 illustrates the C-axis Layout for rotation of C Axis Motor (29) and position of Coupling (30), Table Housing (31), Shaft (32) Coupling (33) Indexing Worm (34) and Worm Wheel (35) according to the present invention.
Fig 5 illustrates X Axis AC Servo Motor with encoder (36), Driving Pulley (37), Driven Pulley (38) and X Axis Ball Screw (39).
The reduction ratio in the EGB to the hob is considerable so that the hob head drive is subjected to only a small load. Hob slide is moved up and down (Z-axis) by AC servomotor (43). Tangential slide is moved in and out (Y-axis) by AC servo motor (40) which is used for hob shifting only as shown in figure 7.
EGB is housed in a panel enclosure. The panel enclosure contains all the electric and electronic components for controlling and operating the machine. With the machine of the present invention index and differential change gears are eliminated for cutting the spur and helical gears. Set up time is minimized since manual operation is eliminated. It is possible to cut any no. of teeth within the machine specifications resulting in a more precise Electronic gear box feature that enhances the machine capability and accuracy.
Fig. 6 illustrates X axis AC Servo Motor with, encoder (36), Driving Pulley (37), Driven Pulley (38) and X Axis Ball Screw (39) and Main Column (2).
Fig, 7 illustrates Y Axis AC Servo Motor with encoder (40), Coupling (41) and Y Axis Ball Screw (42).
Fig. 8 illustrates Z Axis AC Servo Motor with enocder (43), Gear Box (44), Pulley (45 and 46), Brake (47) Axial Slide (3) and Ball Screw (48).

Fig. 9 illustrates Z Axis AC Servo Motor (43), Gear Box (44), Pulley (45 and 46), Axial Slide (3) and Ball Screw (48).
Said machine comprises movement in 5 axes along with one swiveling axis
i. Horizontal Axis (Radial movement of Column) - X Axis
ii. Vertical Axis (Axial Slide of Hob Head)- Z Axis
iii. Cross Axis (Tangential movement of Hob slide) - Y Axis
iv. Swiveling Axis (Hob head swivel) - A Axis
v. Rotary movement (Table rotation with workpiece) - C Axis
vi. Hob rotation - B axis
The workpiece has its axis perpendicular to the Table axis. The Hob comprises of its axis cross to workpiece and Table axis.
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 to +45 degree with respect to hob head slide axis mounted on main column.
The machine also comprises an in built Coolant Tank (16) and Magnetic Chip Conveyor (14) for the removal of chips.
Fig. 10 shows the positive movement directions. Similar numerals have been used to refer to similar features in the invention for the sake of easy understanding.

Linear axes (1) Main Column (X axis)
(2) Tangential slide (Y axis)
(3) Axial slide (Z axis)
Rotation axes (4) Hob head swivel (A axis)
(5) Hob Rotation (B axis)
(6) Work Table Rotation (C axis)
The following are the few non limiting advantages of the present invention
1. Two cut work cycle with feed change or with out feed change.
2. Skip feed
3. Automatic change for no. of teeth and cutting depth
4. Dipping device
5. Taper Bobbing, Crown hobbing / Copy hobbing
6. Automatic feed control
7. Reduction of set time
8. Multicut work cycle.
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 gear hobbing machine comprising, at least one machine bed, a table drive on said machine bed for mounting a workpiece, a Main column (2) moving on said Machine Bed (1), a Tail Stock Column (5) mounted on said machine bed and Table Housing (31), a Hob head (4) associated to a hob head slide, a Control Panel (Electrical panel) equipped with an electronic calculating means for monitoring the entire hobbing process (13) and an electronic gear box.
2. A gear hobbing machine substantially as herein described particularly with reference to the accompanying drawings.
3. A method for hobbing of gear substantially as herein described particularly with reference to the accompanying drawings.