FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A lancing punch holding fixture for use in an Electrical Discharge Machining (EDM) wire cut machine
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli,
Mumbai 400 030, Maharashtra, India, an Indian Company
Inventors
Sudhir Sangwikar of Crompton Greaves Ltd, Stamping Division, Kanjur Marg, Mumbai, Maharashtra, India, an Indian National
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to a lancing punch holding fixture for use in an Electrical Discharge Machining (EDM) wire cut machine. BACKGROUND OF THE INVENTION
A lancing punch is used for punching or creating a partial cut in a lamination sheet such that no portion of the lamination sheet is removed/detached. Such laminations are used in applications such as stator, rotor of fans, motors, pumps. The profile of such lancing punches are varied such as circular, rectangular, etc. Such profiling of the lancing punches is usually done by grinding process in a grinding machine which involves use of an abrasive to wear away the surface of the punch. Profiling of a punch by grinding process is labour intensive and time consuming. Moreover, skilled labour is required to operate on the usually expensive grinding machine. There is a need to profile the lancing punches on an Electrical Discharge Machining (EDM) wire cut machine through which the profiling would be quick, less cumbersome and obviate the need of a skilled labour. For the lancing punch to be profiled on an EDM wire cut machine, there is a need of a fixture to hold the lancing punch in the EDM wire cut machine. OBJECTS OF THE INVENTION
An object of the invention is to provide a fixture for holding a lancing punch in an Electrical Discharge Machining (EDM) wire cut machine.
Another object of the invention is to provide a fixture for holding a lancing punch in an EDM wire cut machine which is simple and easy to use.

DETAILED DESCRIPTION OF THE INVENTION
According to the invention, there is provided a lancing punch holding fixture for use in an Electrical Discharge Machining (EDM) wire cut machine, the fixture comprising a base and a spigot one end of which being held within a hole in the base, the spigot comprising a central bore for receiving the lancing punch therein through a hole continuous with the bore at said one end of the spigot, one end of the lancing punch being held tightly within the said hole in the spigot, the bore being open at atleast one side of the spigot for providing access of the lancing punch therein to the EDM wire cut machine for profiling thereof.
These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,
Fig 1 is an isometric view of a lancing punch holding fixture.
Fig 2 is an exploded view of a lancing punch holding fixture.
Fig 3 is an isometric view of a lancing punch.
As shown in Figs 1 and 2, a lancing punch holding fixture comprises of a base 1 and spigot 2 usually made up of a stainless steel material. However, it can be made up of other metals as well strong enough to withstand high stress and strain. THE base i is a squarish structure having a pre-determined thickness and adapted to be placed and held tightly on the bed of an Electrical Discharge Machining (EDM) wire cut machine (not shown). A through hole 3 is provided within the base 1 for holding one end 4 of the spigot 2 therein. However, the hole 3 may be' a blind hole extending partially into the thickness of the base I from the top surface of the base 1 such that the lower surface of the base 1 remains flat. The size and shape of the hole 3 corresponds to that of the size and shape of the spigot 2, which is usually squarish, to hold the spigot 2 therein tightly.

For further rigidity, threaded holes 5 are provided at the sides 6 of the base 1 through which bolts (not shown) can be tightened against the one end 4 of the spigot 2 disposed within the hole 3 of the base. However, other known mechanisms may also be used for such a tight holding of the spigot 2 within the hole 3 of the base 1. The spigot 2 comprises of a central bore 7 preferably open at all four sides as shown in figs 1 and 2. However, the bore 7 may be open at only one side. The bore 7 is meant to receive a lancing punch 8 (having ends of dissimilar sizes) therein through a hole 9 at the one end 4 of the spigot 2 held within the base 1 and continuous with the bore 7. The end 10 of the lancing punch 8 having a larger size is held tightly within this hole 9 of the spigot 1 by means of bolt(s) (not shown) tightened against it through threaded hole(s) 11 provided at the sides 12 of the corresponding one end 4 of the spigot 1. Preferably, at the other end 13 of the spigot 1, another hole 14 continuous with the bore 7 is provided for holding the other end 15 of lancing punch 8 having a smaller size compared to the hole 9 at the one end 4 of the spigot 2. Preferably, this hole 14 is a through hole to accommodate lancing punches 8 of any lengths. Lancing punches 8 of larger length may extend outside this through hole 14. However, it may also be a blind hole. The other end of the lancing punch 15 may also be held tightly in this hole 14 through bolt(s) tightened against it through threaded hole(s) 16 provided at the sides 17 of the corresponding other end 13 of the spigot 2. However, other known mechanisms may also be used. The opening(s) at the bore 7 is for providing access of the lancing punch 8 to an EDM wire cut machine for profiling the lancing punch 8 to a desired shape, such as the one 18 shown in Fig 3. The lancing punch 8 to be profiled is inserted into the spigot through the hole 9 such that the other end 15 of the lancing punch 8 enters the spigot 2 first and the ends 10 and 15 of the lancing punch 8 are held within the holes 9 and 14 of the spigot 2 respectively. Subsequently, bolts are inserted into the holes 9 and 14 as describe above to hold the

lancing punch 8 within the spigot 2 tightly. Thereafter, the spigot 2 is placed within the hole 3 of the base 1 and further tightened by means of bolts through holes 5 as described above. Next, the fixture is placed within an EDM wire cut machine such that an exposed portion of the lancing punch 8 through one of the opening in the bore 7 is profiled by the EDM wire cut machine. After the profiling is completed, the spigot 2 is removed from the base 1 by removing the bolts and reinserted and held tightly into the base i again after reorienting or changing the side of the lancing punch 8 exposed within the EDM wire cut machine for profiling the another exposed side of the lancing punch 8 through another opening. Such is repeated until a desired shape of the lancing punch 8 is achieved as shown in Fig 3. Finally, the lancing punch 18 with the desired shape is removed from the spigot 2 after removing the spigot 2 from the base.
It will be obvious to a person skilled in the art that the shapes of the base, spigot and the holes therein may vary depending upon the application. Such is true for the shape, size and type of the lancing punch as well.
According to the invention, there is provided a lancing punch holding fixture which is simple, easy to use and can be easily used in an EDM wire cut machine. Thus, the need of a grinding machine is obviated for profiling a lancing punch.
Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the scope of the invention as defined in the appended claims.

We claim:
1. A lancing punch holding fixture for use in an Electrical Discharge Machining (EDM) wire cut machine, the fixture comprising a base and a spigot one end of which being held within a hole in the base, the spigot comprising a central bore for receiving the lancing punch therein through a hole continuous with the bore at said one end of the spigot, one end of the lancing punch being held tightly within the said hole in the spigot, the bore being open at atleast one side of the spigot for providing access of the lancing punch therein to the EDM wire cut machine for profiling thereof.
2. The fixture as claimed in claim 1, wherein the base is anchored on the EDM wire cut machine bed.
3. The fixture as claimed in claim 1, wherein said hole in the base is a blind or a through hole.
4. The fixture as claimed in claim 1, wherein spigot is held tightly in the hole of the base by means of bolts through holes provided at the sides of the base.
5. The fixture as claimed in claim 1, wherein the other end of the spigot comprises of a hole continuous with bore for receiving an other end portion of the lancing punch therein.
6. The fixture as claimed in claim 5, wherein said hole is either a blind hole or a through hole.
7. The fixture as claimed in claim 5, wherein the hole is of a diameter smaller than that of the hole at the said one end of the spigot.
8. The fixture as claimed in claim 1, wherein the punch is held tightly in the spigot at the ends thereof by means of bolts through holes provided at the sides of the ends of the spigot.

9. The fixture as claimed in claim 1, wherein the bore is open at all sides of the spigot.